From akestelo at bellatlantic.net Sat Jul 1 13:05:08 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:21 2003 Subject: [Lf] Interesting web site :-) Message-ID: <395E16B3.8EDDDC86@bellatlantic.net> Cantrell Bill-QA0057 wrote: > fyi... great stuff... > > http://w3.gwis.com/~joelr/gearpix.htm From smishey at mishey.com Mon Jul 3 21:40:08 2000 From: smishey at mishey.com (Shannon Mishey) Date: Thu Jul 3 13:42:22 2003 Subject: [Lf] FW: [WUN] 137 kHz Beacon from Canada Message-ID: <007801bfe550$67962220$fb4bfed8@farm.speakeasy.org> -----Original Message----- From: owner-wun@qth.net [mailto:owner-wun@qth.net] On Behalf Of Kevin Sent: Monday, July 03, 2000 7:23 PM To: wun@qth.net Subject: [WUN] 137 kHz Beacon from Canada LF test transmissions set: Larry Kayser, VA3LK, in Eastern Ontario, Canada, has commenced a series of test transmissions on 137.710 kHz, with very slow CW at 0.4 WPM. The test transmissions will continue until July 30. Kayser asks those able to copy the signal to forward signal reports to va3lk@arrl.net. VA3LK is testing equipment and processes in preparation for the TransAtlantic II attempt on LF set to occur November 10-27 from Newfoundland. The VA3LK tests use the antenna tuning hardware and associated tuning process, the exciter, keying computer for CW, QRS CW, and BPSK, as well as an experimental antenna developed for the fall expedition. Contact Larry Kayser, VA3LK, for more information on this or other test transmissions.--Larry Kayser, VA3LK Kevin -- ----------------------------------------------------------- Check out the HAM-SWL-SCAN-SALE mail list http://www.egroups.com/group/HAMSWLSCANSALE Thought for the day: Advertising (n): the science of arresting the human intelligence for long enough to get money from it. -- Stephen Leacock. --------------------------------------------------------------- --- The Worldwide UTE News (WUN) mailing list. WUN is a non-profit, dues-free club established in 1995 to share information on shortwave utilities. For more information: http://www.wunclub.com/ From akestelo at bellatlantic.net Mon Jul 3 20:27:56 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:22 2003 Subject: [Lf] [Fwd: LF: G0MRF rig in Canada] Message-ID: <3961217B.3AF65ED4@bellatlantic.net> Mitch Powell wrote: > Greetings: For information: > Have just completed G0MRF transmitter, and pictures provided at > http://technology.fanshawec.on.ca/elec316 > I have been transmitting 137.780 test, and also locensed licensed > for135.7-137.8 > and have low power and low antenna but persevering. > This rig certainly was great to build and should help. > > 73 > Mitch From akestelo at bellatlantic.net Mon Jul 3 20:09:21 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:22 2003 Subject: [Lf] LF antennas & ferrite rods Message-ID: <39611D21.5266A210@bellatlantic.net> Rik Strobbe wrote: > At 16:12 3/07/00 +0100, G3XDV wrote: > >Peter, G3LDO, had a worse result and we concluded that the type of ferrite > >was critical (just try putting a broadcast type ferrite rod inside your > >loading coil - it gets VERY hot). Possibly a rod made from SMPU cores would > >work. > > I use a ferrite rod inside a part of the loading coil for fine-tuning my > antenna on 136kHz. I did some testing to minimize losses (and avoid 'melt > down'). > Conclusions were : > - Material is (as expected) very important. Although all my rods are > 'recycled' from old radio's they seem to be made of very different > materials. When I put the rod into the big (5mH) loading coil and gave a 1 > min carrier with 35 Watt the rods got very warm to extemely hot (burnt my > fingers on one). I used that method to find the rod (from my +/- 40 > quantity stock) that got least hot. > - I coupled the rod very 'loosely' to the coil, just enough to get a 0.3mH > variation in a 1mH coil (by sliding the rod up or down). This 0.3mH > variation was enough to cover the 'steps' of the big 5mH coil that can be > tuned in +/- 0.3mH steps (taps). > With this setup the rod hardly warms up, even with 450W RF power. > > 73, Rik ON7YD From akestelo at bellatlantic.net Mon Jul 3 20:04:18 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:22 2003 Subject: [Lf] [Fwd: DDS board] Message-ID: <39611BF2.D648E5A3@bellatlantic.net> Talbot Andrew wrote: > The DDS boards have now been manufactured. AD9850 ICs are currently > being fitted and should be available in a few days, so orders can now be > placed. > > Bare PCBs for those who want to install their own chips are available > for ?8.00 from HF Instruments. Their web address is WWW.HF-INST.CO.UK > and the page will be updated very soon to include the DDS board data. > Programmed PICs for the straightforward ASCII text based command > interface can be made available for anyone who wants them, otherwise PIC > assembly / hex code is available for programming your own. > > Prices for chips mounted on the board as as follows : > > > PCBs fitted with AD9850 chip will be available 7th July. Prices are: > > ?40.00 for one. > > ?38.00 for 2 to 4. > > ?36.00 for 5 to 10 > > ?34.00 for 10+ > > > We introduced the bulk order discounts for the likes of TAPR etc who may > care to distribute. > > My software (DOS) for generating narrow band SMT Hell is free on request > for anyone who purchases one of these boards, also an early not fully > tested version of a SLOWCW / DFCW prog. Both these software communicate > via ASCII Text commands to the DDS module. The source code can be used > as reference material for anyone who wants to produce their own driving > code > > Andy G4JNT > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution,o > r any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From akestelo at bellatlantic.net Sat Jul 1 13:02:45 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:23 2003 Subject: [Lf] Re: [Lowfer] Experimental license for the group? References: Message-ID: <395E1625.69C8A146@bellatlantic.net> Clifford Buttschardt wrote: > [...] > As I understand it, any amateur related STA, although this is not > strictly amateur usually is brought to the attention of Ray Rinaldo who > edits the AMRAD newsletter. Andre, CC'd above probably is the better man > to comment on this approach. I must insist that we apply for an > authorization in which ANY experimenter can participate rather than the > present AMRAD authorization which is limited to specific individuals. > Cliff K7RR ******************************************8 Hello Friends, Apologies for this late reply. I have just returned yesterday from a trip to Europe, and am still wading through a zillion messages in my In-box :-) As I understand it, a STA can only be granted by the FCC as a temporary authorization for amateur radio-operators to do something not normally authorized on a ham-band . (For instance, AMRAD received in the early 80's a STA to experiment with Spread-Spectrum technology on ham bands). As the 136 KHz sliver is not, at the present time, a Ham band, no STA can be issued by the FCC for that frequency. What AMRAD did, instead, was to request a "Part 5" license to operate on 136.750. Such a license demands that the operators' names and locations be clearly spelled out prior to the license being granted. The members of AMRAD that are listed on the Part 5 license all happen to be amateur radio operators, but cannot use that license to communicate with other operators not listed on the license. In other words, when we communicate with one another on 136.750 under that license, we are not hams, we are experimenters. When I transmit on 136.750, I am not N4ICK talking to WB3KDU, but WA2XTF/4 in contact with WA2XTF/6. Meanwhile, the ARRL has also requested from the FCC that both the 135-137 band (similar to the CEPT one available in Europe) and the present "Lowfer" band be designated as amateur bands. AMRAD had nothing to do with that request, as far as I know. Incidentally, the editor of the AMRAD Newsletter is Paul Rinaldo W4RI (w4ri@amrad.org) Hope this helps a little to clarify the present situation :-) 73 Andre' N4ICK From cbuttsch at slonet.org Sat Jul 1 10:16:01 2000 From: cbuttsch at slonet.org (Clifford Buttschardt) Date: Thu Jul 3 13:42:23 2003 Subject: [Lf] Re: [Lowfer] Experimental license for the group? In-Reply-To: <395E1625.69C8A146@bellatlantic.net> Message-ID: Thanks Andre for the reply. It is most unfortunate that many read part fifteen into the original message rather than part five, (I'm included in that fault!) Part five is well defined but it was news that AMRAD also used that. Even better news is that 136 kHz is being considered for a ham band since we here in the West have noticed that the Dixon, CA signal has been off the air for two months! Possibly, AMRAD and William Ashlock would publish the required "boilerplate" used in part five applications. Cliff K7RR On Sat, 1 Jul 2000, Andre' Kesteloot wrote: > Clifford Buttschardt wrote: > > > [...] > > > As I understand it, any amateur related STA, although this is not > > strictly amateur usually is brought to the attention of Ray Rinaldo who > > edits the AMRAD newsletter. Andre, CC'd above probably is the better man > > to comment on this approach. I must insist that we apply for an > > authorization in which ANY experimenter can participate rather than the > > present AMRAD authorization which is limited to specific individuals. > > Cliff K7RR > > ******************************************8 > Hello Friends, > > Apologies for this late reply. I have just returned yesterday from a trip to Europe, > and am still wading through a zillion messages in my In-box :-) > > As I understand it, a STA can only be granted by the FCC as a temporary > authorization for amateur radio-operators to do something not normally authorized on > a ham-band . (For instance, AMRAD received in the early 80's a STA to experiment > with Spread-Spectrum technology on ham bands). > > As the 136 KHz sliver is not, at the present time, a Ham band, no STA can be issued > by the FCC for that frequency. > > What AMRAD did, instead, was to request a "Part 5" license to operate on 136.750. > Such a license demands that the operators' names and locations be clearly spelled > out prior to the license being granted. > The members of AMRAD that are listed on the Part 5 license all happen to be amateur > radio operators, but cannot use that license to communicate with other operators not > listed on the license. In other words, when we communicate with one another on > 136.750 under that license, we are not hams, we are experimenters. When I transmit > on 136.750, I am not N4ICK talking to WB3KDU, but WA2XTF/4 in contact with WA2XTF/6. > > Meanwhile, the ARRL has also requested from the FCC that both the 135-137 band > (similar to the CEPT one available in Europe) and the present "Lowfer" band be > designated as amateur bands. AMRAD had nothing to do with that request, as far as I > know. > > Incidentally, the editor of the AMRAD Newsletter is Paul Rinaldo W4RI > (w4ri@amrad.org) > > Hope this helps a little to clarify the present situation :-) > 73 > Andre' N4ICK > > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net > From akestelo at bellatlantic.net Sun Jul 2 16:13:35 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:23 2003 Subject: [Lf] Waveforms and Fourier analysis Message-ID: <395F945F.B7C709EA@bellatlantic.net> Worth reading, IMHO http://www.dataq.com/applicat/articles/an11.htm Andre' N4ICK From akestelo at bellatlantic.net Sun Jul 2 16:15:05 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:23 2003 Subject: [Lf] LF: SAQ 2nd July] Message-ID: <395F94B8.3C03269A@bellatlantic.net> James Moritz wrote: > Dear LF Group, > I was very pleased to hear SAQ on 17.2kHz again today, with > their 75th anniversary message. In spite of the higher QRN level > compared to the new year event, I had perfect 599 copy of the > signal.The scheduled 0830 utc message apparently did not go out, > although I did hear a carrier for a few seconds around 0825. I > heard them start to tune up again around 1140, and the 1230 > broadcast went ahead as planned. Later, I was able to work SA6Q > on 14MHz, where copy was much more difficult than on 17.2kHz! > > For the new year broadcast I just used my LF antenna in an un- > tuned condition, but for this occasion I tried two new antennas, > both of which worked much better, and something similar could be > of interest for those experimenting on 9kHz - one was a 3m tuned > whip, the other a ferrite rod made from 16 scrap 'U' cores glued > together to make a piece of ferrite 32mm x 36mm x 480mm. Both > antennas were used with a JFET preamp, and were easily able to > hear down to the atmospheric noise level. If anyone would like > details, let me know. > > I also heard the signal just above 18kHz - could this be the Indian > Navy VTX3 station again? This sometimes sends plain CW too. > > Cheers, Jim Moritz > 73 de M0BMU From akestelo at bellatlantic.net Sun Jul 2 16:15:05 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:23 2003 Subject: [Lf] LF: SAQ 2nd July] Message-ID: <395F94B8.3C03269A@bellatlantic.net> James Moritz wrote: > Dear LF Group, > I was very pleased to hear SAQ on 17.2kHz again today, with > their 75th anniversary message. In spite of the higher QRN level > compared to the new year event, I had perfect 599 copy of the > signal.The scheduled 0830 utc message apparently did not go out, > although I did hear a carrier for a few seconds around 0825. I > heard them start to tune up again around 1140, and the 1230 > broadcast went ahead as planned. Later, I was able to work SA6Q > on 14MHz, where copy was much more difficult than on 17.2kHz! > > For the new year broadcast I just used my LF antenna in an un- > tuned condition, but for this occasion I tried two new antennas, > both of which worked much better, and something similar could be > of interest for those experimenting on 9kHz - one was a 3m tuned > whip, the other a ferrite rod made from 16 scrap 'U' cores glued > together to make a piece of ferrite 32mm x 36mm x 480mm. Both > antennas were used with a JFET preamp, and were easily able to > hear down to the atmospheric noise level. If anyone would like > details, let me know. > > I also heard the signal just above 18kHz - could this be the Indian > Navy VTX3 station again? This sometimes sends plain CW too. > > Cheers, Jim Moritz > 73 de M0BMU From akestelo at BELLATLANTIC.NET Thu Jul 6 08:24:50 2000 From: akestelo at BELLATLANTIC.NET (Andre' Kesteloot) Date: Thu Jul 3 13:42:24 2003 Subject: [Lf] the best RX for 136 kHz? Message-ID: <39646C82.DBF7E3B3@bellatlantic.net> Klaus von der Heide wrote: > Klaus, DJ5HG wrote: > > > > After an input filter a low-noise operational amplifier > > > is followed by an analog to digital converter. The receiver > > > structure, the demodulation, noise blanking etc... is entirely > > > programmed on a DSP or on one of the new Million-Gates FPGAs. > > Alberto, I2PHD wrote: > > > I substantially agree, with a precisation : > > depending on the type of demodulation you wish to do on the signal, > > having the I and Q components is of great help. So, why not mix down > > the 137 kHz signal to baseband, using a couple of mixers fed with > > an oscillator that produce two signals in quadrature ? Some DDS have > > this capability, so the +- 90 degrees shifting could also be done > > digitally, reducing the analog part of the receiver to the bare minimum. > > Then the two I and Q components could be fed to the left and right > > inputs of a stereo sound card, and all the processing done on a Pentium, > > which nowadays rivals in processing speed with DSPs that only a few years > > ago were considered state of the art. > > Just food for thought... > > Yes, that is a good design if the hardware effort of the whole system > is to be minimized. Also, if you want to use one of the well-known > DSP-cards as the DSP56002EVM that is the best solution. > The DDS-module of your external front end should be clocked > synchronously with the sampling rate of the analog to digital > converter. That is a little technical problem when you use the > sound card. The A/D-converter of the EVM-board can be clocked from > an external clock. > The second point in favour of the direct way of sampling the 136 kHz > is the better linearity of the digital mixer. > That are the reasons why I prefer to do the DDS and quadrature mix > down to baseband by the DSP. Your design in principle is the same > as mine, only the selection what is done in hardware or software > is different with the result of minimum extra hardware in the case > of the sound card, nice! > > 73 de Klaus, DJ5HG From akestelo at bellatlantic.net Wed Jul 5 09:28:40 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:24 2003 Subject: [Lf] AMIDON site Message-ID: <396329F7.21A1C5BF@bellatlantic.net> hello LF Gang More on rods from Amidon at: http://www.bytemark.com/amidon/rod1.htm Andre' From akestelo at bellatlantic.net Wed Jul 5 09:26:51 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:24 2003 Subject: [Lf] Ferrite rod antennas Message-ID: <3963298B.806D4E4B@bellatlantic.net> Go to > > http://www.st-and.ac.uk/~www_pa/Scots_Guide/RadCom/part7/page5.html for a description of ferrite rods and their uses Andre' -------------- next part -------------- An embedded message was scrubbed... From: "Soegiono, Gamal" Subject: LF: AW: Ferrite rod antennas Date: Wed, 5 Jul 2000 08:38:35 +0100 Size: 1783 Url: http://atanasoff.rf.org/pipermail/lf/attachments/20000705/9615b36b/attachment.txt From akestelo at bellatlantic.net Wed Jul 5 09:29:33 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:24 2003 Subject: [Lf] What is the best RX for 136 kHz?] Message-ID: <39632A2D.898A8EEB@bellatlantic.net> Alberto di Bene wrote: > Klaus von der Heide wrote: > > > > > What is the best RX for 136 kHz? > > > > That depends on what you personally mean by "best" > > (cheapest, most versatile, best IP, frequency stability ...) > > > > My personal goal is to be able to adapt to any situation. > > >From this point of view the "best" receiver is the following: > > > > After an input filter a low-noise operational amplifier > > is followed by an analog to digital converter. The receiver > > structure, the demodulation, noise blanking etc... is entirely > > programmed on a DSP or on one of the new Million-Gates FPGAs. > > > > 73 de Klaus, DJ5HG > > > > I substantially agree, with a precisation : > depending on the type of demodulation you wish to do on the signal, > having the I and Q components is of great help. So, why not mix down > the 137 kHz signal to baseband, using a couple of mixers fed with > an oscillator that produce two signals in quadrature ? Some DDS have > this capability, so the +- 90 degrees shifting could also be done > digitally, reducing the analog part of the receiver to the bare minimum. > Then the two I and Q components could be fed to the left and right > inputs of a stereo sound card, and all the processing done on a Pentium, > which nowadays rivals in processing speed with DSPs that only a few years > ago were considered state of the art. > Just food for thought... > > Alberto I2PHD From akestelo at bellatlantic.net Fri Jul 7 09:32:35 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:25 2003 Subject: [Lf] The best LF Receivers] Message-ID: <3965CDE3.7D504E75@bellatlantic.net> Talbot Andrew wrote: > Alternatively, if you want to do a bit more analogue signal processing > to get some good filtering of adjacent strong signals, and have fun > building a custom top grade receiver :- > > Use a DDS derived LO locked to a master reference to mix up to an IF of > 455 kHz. Get hold of some mechanical filters with 300 Hz bandwidth or > lower and and bandpass filter / amplify. Mix back down with a 456k BFO, > again derived from the same reference to give a signal centred on 1kHz. > A sampling mixer could be used here driven with 8kHz at this is easy to > get from a 5 or 10MHz reference by division without resorting to a > second DDS or synth. The output can be fed to an audio amp for > inefficient ear / brain based reception and is the ideal centre > frequency for off-the-shelf Soundcard software such as PSK31, SPECTRAN > etc. The -60dB bandwidth has to be 400 Hz or less.. > > Undersample the 1kHz in a 12 - 16 bit A/D converter, at a clock rate of > 800Hz (also locked to the reference) which will have the effect of > apparantly mixing the signal down by the clock to the band 0 - 400 Hz. > For looking at signals in the noise, even 8 bit sampling will work > adequately, the greater dynamic range is only relevant when the S/N is > high enough to require this level of digitisation. Feed the digitised > samples to a PC via the serial port and write (or get written) custom > software that works on this data instead of all the complications of > using the Soundcard. Alternatively, sample in I/Q at 1kHz, mixing down > to zero IF in the process. > > Believe me, driving the Soundcard is by far the most complex part of > doing any DSP work on a PC and puts off many software authors who want > to concentrate on writing decent software than interfacing to Windows ! > It is so messy being forced to use Windows that I haven't even tried > going this route. When time and other projects permit, I will be > making an LF Rx to this design and writing my own software for display > and filtering that will run on any old PC using DOS rather than having > to use the latest Win 95 technology just to drive the A/D converter. > > In the past, using an 8 bit A/D based on a 16C71 PIC plus PC I have seen > signals that are -20dB S/N in a 300Hz CW filter, using custom > Spectrogram type software written in the Basic programming language. > > Andy G4JNT > > > ---------- > > From: Klaus von der Heide[SMTP:v.d.heide@on-line.de] > > Reply To: rsgb_lf_group@blacksheep.org > > Sent: 2000-07-06 10:01 > > To: rsgb_lf_group@blacksheep.org > > Subject: Re: LF: What is the best RX for 136 kHz? > > > > Date sent: Wed, 05 Jul 2000 11:29:11 +0200 > > From: Alberto di Bene > > Organization: Undisclosed > > To: rsgb_lf_group@blacksheep.org > > Subject: Re: LF: What is the best RX for 136 kHz? > > Send reply to: rsgb_lf_group@blacksheep.org > > > > > > Klaus, DJ5HG wrote: > > > > > > After an input filter a low-noise operational amplifier > > > > is followed by an analog to digital converter. The receiver > > > > structure, the demodulation, noise blanking etc... is entirely > > > > programmed on a DSP or on one of the new Million-Gates FPGAs. > > > > Alberto, I2PHD wrote: > > > > > I substantially agree, with a precisation : > > > depending on the type of demodulation you wish to do on the signal, > > > having the I and Q components is of great help. So, why not mix down > > > the 137 kHz signal to baseband, using a couple of mixers fed with > > > an oscillator that produce two signals in quadrature ? Some DDS have > > > this capability, so the +- 90 degrees shifting could also be done > > > digitally, reducing the analog part of the receiver to the bare > > minimum. > > > Then the two I and Q components could be fed to the left and right > > > inputs of a stereo sound card, and all the processing done on a > > Pentium, > > > which nowadays rivals in processing speed with DSPs that only a few > > years > > > ago were considered state of the art. > > > Just food for thought... > > > > > > Yes, that is a good design if the hardware effort of the whole system > > is to be minimized. Also, if you want to use one of the well-known > > DSP-cards as the DSP56002EVM that is the best solution. > > The DDS-module of your external front end should be clocked > > synchronously with the sampling rate of the analog to digital > > converter. That is a little technical problem when you use the > > sound card. The A/D-converter of the EVM-board can be clocked from > > an external clock. > > The second point in favour of the direct way of sampling the 136 kHz > > is the better linearity of the digital mixer. > > That are the reasons why I prefer to do the DDS and quadrature mix > > down to baseband by the DSP. Your design in principle is the same > > as mine, only the selection what is done in hardware or software > > is different with the result of minimum extra hardware in the case > > of the sound card, nice! > > > > 73 de Klaus, DJ5HG > > > > > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution, > or any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From akestelo at bellatlantic.net Fri Jul 7 16:12:46 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:25 2003 Subject: [Lf] programming for Windows Message-ID: <39662BAD.1BA3D08D@bellatlantic.net> Rik Strobbe wrote: > I agree with Andy and Bill, I am using Delphi for programming under windows > (ea. QRS) and accessing the PC soundcard is a real pain. The only driver I > found working more or less satisfying is commercial and costs over 300 USD. > Some freeware drivers I found were excellent tools to crash my PC. > I have also my doubts about the accuracy and stability of the data > aquistition with a soundcard. > But the one BIG advantage is that is available in any multimedia PC and > there are no additional cost and/or work for the users. So, although the PC > soundcard may not be suitable for a 'top end' DSP system it is an easy way > to get started with it. > > Regarding 8-bit vs. 16-bit ADC : main difference is the dynamic range that > is (or should be) over 40dB better for a 16dB card. The 48dB dynamic range > that a 8-bit ADC offers might be a bit less in some applications. But there > are a number of cheap 12-bit ADCs with serial output that can be used, with > a dynamic range of 72dB these might be very suitable. Using 115kB data > transfer via the serial port sample rates up to 7.5kHz are possible. > > 73, Rik ON7YD > > At 10:34 7/07/00 -0400, you wrote: > >At 01:06 PM 7/7/00 +0100, Andy, G4JNT wrote: > > > >>Believe me, driving the Soundcard is by far the most complex part of > >>doing any DSP work on a PC and puts off many software authors who want > >>to concentrate on writing decent software than interfacing to Windows ! > >>It is so messy being forced to use Windows that I haven't even tried > >>going this route. > > > >Well said! > > > >I have a version of CRUNCH that uses the SB16 sound card > >instead of my usual 8-bit Sigma-Delta serial port interface. > >I haven't decided whether to release it because I don't want to > >hear a chorus of criticism from the Windows people. > > > >I know everyone wants Windows software because that's what they've > >been programmed to want by Microsoft hype. So far I have not found > >any version of Windows that is capable of running this new program. > >Why should I go to the trouble of making things compatible with > >some glorified "etch-a-sketch" operating system when I have already > >"upgraded" my computer to DOS? :-) > > > >Let the Windows people write their own software. > > > >Sound cards have other problems... There seem to be a lot of different > >versions out there. And the sampling rate isn't very precise. For > >slow BPSK work where frequency and long-term timing accuracy are > >important you pretty much have to customize each copy of the program by > >calibrating against the specific soundcard it will be running on. > > > >I'm not willing to go to the trouble of supporting umpteen different > >sound card configurations when I'm giving out free software. Don't > >expect me to play by your rules. > > > >>When time and other projects permit, I will be > >>making an LF Rx to this design and writing my own software for display > >>and filtering that will run on any old PC using DOS rather than having > >>to use the latest Win 95 technology just to drive the A/D converter. > > > >Bravo! > > > >>In the past, using an 8 bit A/D based on a 16C71 PIC plus PC I have seen > >>signals that are -20dB S/N in a 300Hz CW filter, using custom > >>Spectrogram type software written in the Basic programming language. > > > >Similar results here. When looking for weak signals in noise, I have > >yet to find any significant difference between 16-bit sound card audio > >and 8-bit audio from my S/D board coming in through a serial port. There > >is likely a narrow range of band conditions under which the sound > >card's 16 bits would be marginally advantageous, though. That's why > >I'm playing with it. > > > >Bill VE2IQ > > > > > > From fgentges at mindspring.com Sat Jul 8 18:10:07 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:25 2003 Subject: [Lf] Throb Message-ID: <396798AF.ED5D90EB@mindspring.com> Thanks to AMRAD member Shannon Mishey for pointing out Throb. It might have some merit, perhaps with variation, for weak signal LF comms. A major downside is the need for a linear power amplifier. You can find out about it at . Frank -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From riese-k3djc at juno.com Sun Jul 9 12:28:12 2000 From: riese-k3djc at juno.com (Bob RIESE) Date: Thu Jul 3 13:42:25 2003 Subject: [Lf] An Idea Message-ID: <20000709.112813.-188507.1.riese-k3djc@juno.com> Hello all A friend just hit me with one of those " why didnt I think of it " As computer ribbon cable is a hamfest item and pretty inexpensive he suggested tieing the ends together and using it as LITZ wire. This would make a wire that would be a little unwieldy but for large antennas etc. it should work well. Ideas / comments Bob K3DJC From akestelo at bellatlantic.net Sun Jul 9 13:01:06 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:26 2003 Subject: [Lf] The situation in Canada Message-ID: <3968A1C1.287A3ED9@bellatlantic.net> Larry Kayser wrote: > Greetings: > > Jim Moritz was inquiring..... > > >Some equipment, antenna, etc. details of the 137kHz beacons > >currently running in Canada and the USA would be interesting. > > I had thought that maybe even to much information had been put out about > what is going on here in Canada - but in any case maybe a summary would be > of interest. > > Here at VA3LK, a test transmitter is located at my remote HF site, just > outside the village of Westport, on top of the ridge. The tower is a self > supporting 240 ft heavy route microwave radio tower. For LF I have about > 340 ft of wire that runs from the bottom of the tower up to the top of the > tower, with an insulator at the top of the tower, and pulled away from the > side of the tower by a rope tied out to a tree about 300 odd feet a way. > The antenna looks very much like a left arrow key i.e. is a small single IRF540 with a variable supply, at the moment running BPSK > for the next few days, or QRS CW at .4 wpm. The DC power input is about 18V > dc at 4.2 Amps or so. The main loading coil is a 18 inch diameter by 18 > inch high with a tap point every two turns. An additional small coil 6 > inches in diameter and 13 inches long raises the total coil to about 2.8 mH. > This facility has been used to test and calibrate two RF units that sample > Voltage and Current and feed an older scope as well as a home made rf > ammeter that is soon to be permanently mounted at the top of the antenna > coil. The exciter is a DDS unit that also has built in BPSK modulator. The > main work at the moment now is final packaging of two different 1 KW plus > amplifiers, making them reliable and also getting familiar with the issues > of having a significant amount of RF at LF in the shack. The test > transmissions with the little amplifier are copied widely in Canada and the > USA, many stations report the signal visible on a 7x24 basis which I find > surprising. The little transmitters purpose is to tune up antennas before a > large amplifier is committed to the antenna. > > I am negotiating for two semi trailer loads of used simplex power service > wire - if I am successful in getting the donation the ground system at the > remote site will consist of several hundred radials at lengths up to 500 > feet or more over the next year or so. This should help the LF signal from > here significantly. > > Mitch, VE3OT now has a license here for 135.7 to 137.8 as well, I will leave > it to him to speak to his work. A third LF license on the East Coast of > Canada should be announced and on the air shortly. The methodical > preparations for TransAtlantic II this coming November in Newfoundland > continue. I have just purchased a new vehicle here, a Van, so the trip to > VO1 will be in a little more comfort than it would be in my old truck. > > Larry > VA3LK From akestelo at bellatlantic.net Sun Jul 9 17:31:20 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:26 2003 Subject: [Lf] Throb References: <396798AF.ED5D90EB@mindspring.com> Message-ID: <3968E118.E1702AB6@bellatlantic.net> Frank Gentges wrote: > Thanks to AMRAD member Shannon Mishey for pointing out Throb. It might > have some merit, perhaps with variation, for weak signal LF comms. A > major downside is the need for a linear power amplifier. a) PSK31 also uses the linear amplifier of your HF rig b) as for LF work, I am still of the opinion that nothing can beat looooong integration times, QRSS 73 Andre' From akestelo at bellatlantic.net Mon Jul 10 11:21:04 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:26 2003 Subject: [Lf] DDS and spurs Message-ID: <3969DBD0.47EB1C21@bellatlantic.net> Johan Bodin wrote: > Hello All, > > At first sight, the DDS may look as an ideal frequency source > for LF. This may be true for transmitters but not for receivers! > In-band spurious signals are generated due to the limited > DAC resolution. These spur's are predictable, to some extent, > but still unavoidable. Depending on the phase increment, the > frequency setting, the spur's may show up very close to the > wanted frequency. > > Popular DDS chips, such as AD9832 and AD9850, have 10-bit > DACs and about 60 dB SFDR (spurious free dynamic range). > LO spur's at -60 dBc may seem harmless but imagine such a > spur mixing with, for example, DCF39 producing a signal right > on top of the weak signal you are trying to receive... > > If strong unwanted signals are present at the mixer input, a > receiver is never better than it's LO. > > The DDS signal can be spectrally "purified" by putting a > "clean-up PLL", with a good VCO, after the DDS and LPF. > The PLL acts as a flywheel. Spur's further away from Fc > than the loop filter BW will be rejected. > > Another option is to make the receiver almost totally digital. > The only analog parts would be a preselector filter and a > preamplifier. A suitable ADC for LF is the AD9260. It is a > 16-bit oversampling ADC (20 MHz) with Fs/8 decimation > (decimation filters are on-chip). Input BW is 1 MHz and > output Fs=2.5 MHz. The output from the ADC can be fed into > an Intersil (formerly Harris) HSP50016 downconverter chip. > The HSP50016 has a quadrature DDS LO (the actual tuning), > digital I/Q mixers, programmable decimation, main I/Q filters > (FIR) and a serial data output. The output can be fed to a DAC, > for direct audio output, or a complex signal can be fed to a DSP > for further processing. The RX BW depends on the selected > decimation ratio and the filter skirts are STEEP! > The HSP50016 has a lot of different output formats, both > complex (I/Q) and real (Weaver method). > > 73 de Johan, SM6LKM From akestelo at bellatlantic.net Mon Jul 10 19:20:54 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:26 2003 Subject: [Lf] Nato transmissions Message-ID: <396A4C45.B10186C8@bellatlantic.net> RTTY/CW station on 82.750 Khz Costas Krallis wrote: > At 10:39 10/07/2000 -0700, you wrote: > > > Thanks for confirming my suspicions. The only thing that I am still puzzled > > about is the station being called, 5DQ, that sounds like Morocco - is that > > possible? > > These trigraphs are NATO callsigns and/or recipient indicators > and change daily. Their structure is random. > > > Strangely I cannot find RTTY settings that seem to produce the same sort of > > text though. > > The RTTY signal is encrypted with an on-line security device. > For similar transmissions try 4731 kHz during local evenings. > > Costas > > +------------------------------------------------------------+ > | Costas Krallis SV1XV * LOC KM18UA | > | P.O.Box 3066 * FAX: +30-1-3811362 | > | GR-10210 Athens * E-Mail: sv1xv@eexi.gr | > | GREECE * PGP key: 0x3BDBBC34 | > +------------------------------------------------------------+ -------------- next part -------------- An embedded message was scrubbed... From: Costas Krallis Subject: LF: MKL (Was: RTTY/CW station on 82.75kHz) Date: Mon, 10 Jul 2000 22:17:37 +0300 Size: 2408 Url: http://atanasoff.rf.org/pipermail/lf/attachments/20000710/691d0be1/attachment.txt From akestelo at bellatlantic.net Tue Jul 11 10:47:20 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:27 2003 Subject: [Lf] A useful site Message-ID: <396B2568.3514F19A@bellatlantic.net> The site below offers specs and links for most semiconductors http://www.bgs.nu/sdw/s.html The above site is a Mega links site which can take you straight to the datasheet site of any manufacture you can think of. From akestelo at bellatlantic.net Tue Jul 11 18:21:13 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:27 2003 Subject: [Lf] DDS and spurs Message-ID: <396B8FC9.2F95027A@bellatlantic.net> Graeme Zimmer wrote: > Johan Bodin wrote > > > At first sight, the DDS may look as an ideal frequency source > > for LF. This may be true for transmitters but not for receivers! > > [snip] > > > In-band spurious signals are generated due to the limited DAC resolution. > > Having built a number of DDS's using discrete ICs, I feel I can add to > Johan's comments.. > > The worst spurs are caused by the fact that the DDS is unable to change it's > output except at the clock edges. > At frequencies where the output is an exact sub-multiple of the clock, a > very clean signal is obtained. > But at all of the intermediate frequency steps, the DDS is actually > jittering between the two nearest sub-harmonics. > It is this FM modulation which causes the worst spurs and this sadly has no > direct cure. > > The spurs caused by the DAC can be reduced by using more bits in the system, > but the FM spurs can only be reduced by using a (much) higher clock > frequency (there are various other schemes of course). > > > Another option is to make the receiver almost totally digital. > > The trouble here is that any digital RX will still need a digital VCO (NCO > or DDS) which will always have the above inherent FM spur problem. If the > DDS is in software, it will of course have a much lower clock frequency > (instruction step) than the hardware DDS chips. > > I would love to be proven wrong in this rather pesimistic analysis... > > coments anyone ? > > ................... Zim .................. VK3GJZ From akestelo at bellatlantic.net Tue Jul 11 18:22:10 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:27 2003 Subject: [Lf] [Fwd: LF: AOR 7030 sensitivity at VLF] Message-ID: <396B9002.BC3C9B68@bellatlantic.net> Alan Melia wrote: > Hi all, John, G4CNN, raised the point of the sensitivity of the AOR 7030 > receiver, which is specified to go down to " 0Hz" !! I knew it fell of a > bit as SAQ was nowhere near as strong on the S-meter as I expected it to be. > So I carried out the measurement tabulated below this evening using a > Marconi TF2002B down to 10kHz, using the attenuator. Below 10kHz I used a > Farnell DSG1 Synth audio gen with 10dB step attenuator and a pot to > interpolate with a moving coil meter reading (both relative to 50 ohms). The > frequency is that shown on the generator, and the measurement was made in > LSB mode with a 1000Hz tone. So the rx was indicating 1kHz higher than the > generator. The internal preamp in the 7030 was switched in. The generator > was adjusted to read S9 on the LCD scale (which has a resolution of 1dB, > although the scale is not quite that linear) > > Frequency TF2002B DSG1 > in kHz in uV in mV > 137 45 > 100 45 > 75 45 > 50 70 > 35 80 > 25 220 > 20 900 > 15 5000 > 10 80,000 70 > 9 150 > 8 325 > 7 650 > > The ultimate sensitivity of my 7030 using Spectrogram or Spectran is > approximately > -80dB relative to S9 at 136kHz. A good audio preamp would be better below > 10kHz!! > What should we be aiming at as a practical usable sensitivity, considering > we will probably be using milliHz bandwidths? > > Cheers de Alan G3NYK > Alan.Melia@btinternet.com From akestelo at bellatlantic.net Tue Jul 11 18:23:38 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:27 2003 Subject: [Lf] more on DDS Message-ID: <396B905A.9C608805@bellatlantic.net> Klaus von der Heide wrote: > From: "Johan Bodin" > To: > Subject: SV: LF: What is the best RX for 136 kHz? > Date sent: Mon, 10 Jul 2000 00:23:35 +0200 > Send reply to: rsgb_lf_group@blacksheep.org > > Johan, SM6LKM wrote > > > At first sight, the DDS may look as an ideal frequency source > > for LF. This may be true for transmitters but not for receivers! > > In-band spurious signals are generated due to the limited > > DAC resolution. > > Yes, that's the reason why I simply divide the 24576 kHz of the > oscillator of the A/D-converter on my DSP-boards by 64*3 to get > 128 kHz as an LO for shifting down the 136 kHz to AF. > The LF-band is so narrow that a DDS is not neccessary. > > > Another option is to make the receiver almost totally digital. > > The only analog parts would be a preselector filter and a > > preamplifier. > > That was just my first answer to Petr's question on this subject. > But amateurs like mixing their signals hence and fourth, and so > this discussion came up. > > > A suitable ADC for LF is the AD9260. It is a > > 16-bit oversampling ADC (20 MHz) with Fs/8 decimation > > (decimation filters are on-chip). Input BW is 1 MHz and > > output Fs=2.5 MHz. The output from the ADC can be fed into > > an Intersil (formerly Harris) HSP50016 downconverter chip. > > The HSP50016 has a quadrature DDS LO (the actual tuning), > > digital I/Q mixers, programmable decimation, main I/Q filters > > (FIR) and a serial data output. The output can be fed to a DAC, > > for direct audio output, or a complex signal can be fed to a DSP > > for further processing. The RX BW depends on the selected > > decimation ratio and the filter skirts are STEEP! > > The HSP50016 has a lot of different output formats, both > > complex (I/Q) and real (Weaver method). > > I let one of my students design a similar chip, but fully > programmable with a finite state machine and additionally > DDS-generators for frequency shifting on board. Using a > 0.25 micron technology and 5 metal layers the chip covers > the entire HF-region as input. The programmability enables > reception on many frequencies at different bandwidths at the > same time on the same tiny chip (3*3 mm). > > But, such a chip in our case is not neccessary because: > > (1) The LF-band is only 2 kHz in bandwidth. Therefore it is > possible to undersample at very low rate directly, say 32 kHz, > presumed an input filter supresses any aliases sufficiently. > A simple DSP then could analyse the signals without the use > of an Intersil/Harris-chip. I am searching for an 16 bit-A/D- > converter without alias filter or with an disable for it. > Another possibility is to throw away 79 of 80 samples when > using the AD9260. > > (2) Using sophisticated multirate technique it is possible > to run any desired bandpass filter on a modern DSP at an > input rate of up to the high output rate of the AD9260. > > 73 de Klaus, DJ5HG From PowellM at claven.fanshawec.on.ca Wed Jul 12 00:18:54 2000 From: PowellM at claven.fanshawec.on.ca (Mitch Powell) Date: Thu Jul 3 13:42:27 2003 Subject: [Lf] Re: Test 137.780 Message-ID: <200007120423.XAA08302@atanasoff.amrad.org> > Hence, please let us all know (see above ) what speed > you will be transmitting at, dot length in seconds, etc etc. Thanks for the quick response. FYI - Freq 137.780 and sending VE3OT and code speed is 0.4 WPM Dots appear to be 2.5-3 seconds and dashes 9 seconds. I will be leaving it on 24 hours - and seems best signals and lowest noise occur in the early morning - though lately they have been good right up until mid-day. Using vertical polarization here. Power input 150 watts at present and measured >80% efficiency. Just out on a quick trip to the country, and great signal at 15 miles - let's hope it goes a bit farther. I really appreciate your passing the info along - with this antenna and time of year, it will be a challenge. Mission Impossible 3 - hi ! 73 Mitch VE3OT From akestelo at bellatlantic.net Tue Jul 11 22:59:10 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:28 2003 Subject: [Lf] [Fwd: LF: SAQ circuit diagram] Message-ID: <396BD0EE.3FC29EAE@bellatlantic.net> Dick Rollema wrote: > To All from PA0SE Because I want to write a note on SAQ in our VERON > magazine Electron I asked the Grimeton people for some > photographs. As a result I received beautiful pictures and also the > circuit diagram of the alternator transmitter. When you want to see > the diagram just sent me an e-mail and I will forward it to you as > attachment (23.7 kB) to a direct e-mail. I have received permission > from Grimeton to do so. 73, Dick, PA0SE From akestelo at bellatlantic.net Tue Jul 11 23:01:01 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:28 2003 Subject: [Lf] Elevated Ground Plane] Message-ID: <396BD15D.2642B11C@bellatlantic.net> Richard Brunner wrote: > Bill wrote: > "Does anyone use an elevated ground-plane for their lowFER beacon?" > > I believe TH has, for many years. My experience is that an elevated ground > plane, or counterpoise, is vastly better than any experimenters ground grid. > When operating as 1RB some years ago, I was heard at 900+ miles in Illinois, > and would have done much better with a counterpoise. With the same antenna > on 160M, on a whim I tried a simple two wire counterpoise, and impedance > dropped from 85 Ohms to 16.5 Ohms, and antenna current increased from less > than 1 amp to 2.5. My ground grid looked more like a 50 Ohm dummy load. I > never tried it, but the gain on lf would have been substantial. Here in New > England I have poor ground conductivity with rocks, sand, and gravel. You > may do better, but remember, a counterpoise is vastly easier to install than > an effective ground grid. (You haven't lived 'till you trip on your own > ground grid.) Counterpoises were also used on the old lf and vlf high power > stations, and worked as well or better than ground grids. They eventually > favored ground grids because there was no maintenance, and the counterpoises > occasionally started field fires, presumably due to arcing to the > vegetation. > > Richard Brunner, rbrunner@gis.net > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Tue Jul 11 22:58:26 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:28 2003 Subject: [Lf] Re: Test 137.780 References: <20000711221522.GMJJ493.immta3.bellatlantic.net@claven.fanshawec.on.ca> Message-ID: <396BD0C2.6CC9624A@bellatlantic.net> Congratulations, Mitch. I am sending this reply cc: to the AMRAD LF group, and those who have decent receiving systems will, I am sure, be looking for your signal. When one uses Spectran to look for weak signals, it is most important to know in advance what one is looking for, as one needs to optimize the speed, integration time, etc. Hence, please let us all know (see above ) what speed you will be transmitting at, dot length in seconds, etc etc. 73 Andre' ***************************** Mitch Powell wrote: > Good Day Andre: > Just a quick note for your information. > Finally have G0MRF rig working - after > correcting a few mistakes I made as I > assembled the unit. > > Will be sending callsign on 137.780 . > Looks like quiet weather here and low noise noise levels > so I would appreciate any attempts at hearing > the signal. Maybe you might mention it to some > of your friends. > > Presently measuring over 900 mA into the vertical > and shouldn't have tried it - but with a pencil I > am able to draw 1/2 inch arcs from the top of the > coil and the antenna proper. Something must be > happening. > > Vertical is 50 foot Marconi - with 2.5-3.5 mH coil at > bottom and variometer tuning. And pretty well > surrounded by maple and spruce trees :-( > > Thanks and 73 > > Mitch VE3OT From akestelo at bellatlantic.net Thu Jul 13 10:43:45 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:29 2003 Subject: [Lf] even more on DDS Message-ID: <396DC790.562F5A75@bellatlantic.net> Klaus von der Heide wrote: > From: "Graeme Zimmer" > To: > Subject: Re: LF: What is the best RX for 136 kHz? > Date sent: Tue, 11 Jul 2000 12:54:32 +1000 > Send reply to: rsgb_lf_group@blacksheep.org > > Zim, VK3GJZ wrote: > > > The worst spurs are caused by the fact that the DDS is unable to change it's > > output except at the clock edges. > > Definitely no! The sampling theorem in a DDS never is violated. Spurs > only can be produced by non-linearity. One source is, as Johan wrote: > > > > In-band spurious signals are generated due to the limited DAC > resolution. > > DDS means Direct Digital Synthesis. The main source of non-linearity > is the generation of the sine function itself. Usually a lookup table > is used plus a cubic interpolation or a Taylor expansion of third > order. I use the latter in my DDS-implementation on the DSP. It is > accurate in 23 bits causing no spurs above -135 dB. If the Taylor > expansion is omitted the lookup table must be very very large to > avoid spurs (note: it's totally digital, there is no ADC). > So, if there are spurs I would guess the sine implementation is not > as accurate as you want. This error vanishes when the interpolation > is made for time points exactly lying on one of the points of the > lookup table. That is just your observation: > > > At frequencies where the output is an exact sub-multiple of the clock, a > > very clean signal is obtained. > > But at all of the intermediate frequency steps, the DDS is actually > > jittering between the two nearest sub-harmonics. > > I guess, then only the nearest table point is chosen for output > instead of a correct interpolation. > > > The spurs caused by the DAC can be reduced by using more bits in the system, > > but the FM spurs can only be reduced by using a (much) higher clock > > frequency (there are various other schemes of course). > > No, the clock must be more than twice the output sine frequency. > That's all. > > > > Another option is to make the receiver almost totally digital. > > > > The trouble here is that any digital RX will still need a digital VCO (NCO > > or DDS) which will always have the above inherent FM spur problem. If the > > DDS is in software, it will of course have a much lower clock frequency > > (instruction step) than the hardware DDS chips. > > In a DSP-solution the samples are computed for virtual time steps. > There is no relation between these time steps and instruction step or > the processor clock. A conversion from virtual time steps (as on an > audio CD) to real time is done by the A/D-converter. Therefore only > the clock of the ADC determines the accuracy of frequencies in > DSP-solutions, not the DSP-clock. > > As I said above, a DDS-routine for a DSP can be programmed to any > precision. That is the reason why I prefer the almost totally digital > receiver based on a programmable DSP. > > > I would love to be proven wrong in this rather pesimistic analysis... > > I hope I achieved that success. > > Thanks to Johan and Zim for their comments and to Petr for his root- > question! Otherwise this clarification would not have been possible. > > 73 de Klaus, DJ5HG -------------- next part -------------- An embedded message was scrubbed... From: "Klaus von der Heide" Subject: Re: LF: What is the best RX for 136 kHz? Date: Wed, 12 Jul 2000 09:05:19 +0200 Size: 4512 Url: http://atanasoff.rf.org/pipermail/lf/attachments/20000713/70aea977/attachment.txt From akestelo at bellatlantic.net Thu Jul 13 18:19:35 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:29 2003 Subject: [Lf] [Fwd: LF: VLF Sensitivity - Noise Levels] Message-ID: <396E3267.FFA7A50E@bellatlantic.net> James Moritz wrote: > Dear LF Group, > Regarding the recent comments about receiver sensitivity at > VLF - I did some measurements with my 'SAQ' ferrite rod antenna, > and some Helmholz coils I made for 136kHz measurements to > generate a known field strength. > > The atmospheric noise is all of an impulsive, thunderstorm type, so > it's difficult to measure in a meaningful way, but I can say that a > 30uV/m field strength is audible at 17.2kHz, and 50uV/m at 9kHz, > with the current QRN levels - presumably this situation would be > improved during the winter, but I don't know by how much. I was > using 100Hz bandwidth - spectrogram would do better of course. > > By way of comparison, SAQ measured in at about 750uV/m. I > reckon this means about 20kW ERP, very approximately. > > I found that having either the ferrite rod, or the tuned whip antenna, > near the mains wiring of the house produced significant 50Hz > QRM, but moving both antennas 5m away from the house reduced > the noise on the rod to an inaudible level, but still detectable on the > whip, although not serious. > > Cheers, Jim Moritz > 73 de M0BMU From akestelo at bellatlantic.net Fri Jul 14 19:09:22 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:29 2003 Subject: [Lf] DDS Sources in receivers] Message-ID: <396F8F92.65AD2316@bellatlantic.net> Klaus von der Heide wrote: > Andy, G4JNT wrote: > > > A DDS does indeed generate spurious products, but these are precisely > > characterisable and at a level defined by the chip manufacturer. Apart > > from image and harmonics, they are a function of the DDS process and NOT > > SUBJECT to poor layout construction etc whereas a phase locked loop > > synthesizer is unbelievably sensitive to noise etc in the control > > circuitry caused by poor design. Furthermore, the spurs are usually > > well away from the wanted frequency so properly applied filtering will > > eliminate any possible spurious responses. > > In my previous mail I pointed out, that the spurs generated by a DDS > are due to an imprecise implementation of the sine function. This > imprecision is a result of a compromise between the diverging goals, > speed and precision. > The spurs can be made as low as you want. They are a consequence of > the DDS-IMPLEMENTATION, not of the DDS-PRINCIPLE. If you base > the design on a loadable sine table of variable length, you will > be able to work entirely without spurs in almost all cases. > > Example: You want to generate 19.200 kHz on a DSP at a sample rate > of 48.000 kHz. Generate a sine table of the 5 values > sin(2*pi*k/5) with k = 0,1,2,3,4 and wrap around in this table > at a step of 2. Interpolation is not neccessary, so no spurs. > > Hardware implementations mostly use ROM-sine-tables of fixed size. > Then sine values at phases between adjacent table points have to be > computed. Example: > The same situation as above; use a sine table of 256 values. > Let the first phase be 0, then the second is p = (0 + step)mod 256 > where step = 256*19.2/48.0 = 102.4 > To calculate sine(2*pi*p/256) the nearest table point p0 to p > is chosen, i.e. in the above example: p = 102.4; p0 = 102; > p1 = 0.4 with p = p0 + p1 > Let s = table(p0) (the sine value from the table) > and c = table((p0+64)mod 256) (the correspondent cosine value) > and dp = p1*2*pi/256 . > Then compute x = s + dp*(c - dp*(s/2 + dp*c/6)) (Taylor-series) > Using this simple algorithm the value x never differs from the exact > sin(2*pi*p/256) by more than 5e-9. Spurs are less than -165 dB. > > Implementation of this algorithm on a DSP costs about 30 instruction > cycles in contrast to only one if simply the nearest lower table > point is taken. The gain achieved by this factor 30 in computational > effort is about 130 dB in spur suppression. > > It is this hardware (or software) simplification that causes the > spurs, not the DDS in principle. Surely future DDS-chips will > use advanced algorithms to minimize spurs. > > > Any one who advocates using a PLL just to 'clean up' a DDS is > asking for > > the worst of all worlds. > > The phase noise of a PLL is proportional to the frequency division > factor used in the PLL. A clean-up-PLL will not use any divider. > So the phase noise could be kept low. But, off course, it will be > present at the win of very low spurs. Nevertheless, I prefer a more > precise DDS-implementation instead of such a clean-up which would > reduce the usable frequency range. > > Two years ago I made my own board with four synchronous AD9850 > driven individually via the printer port. That is very valuable > for many purposes. In fact, I also use this board in receiver > applications, especially where frequency stability is the main > point. > > 73 de Klaus, DJ5HG From akestelo at bellatlantic.net Fri Jul 14 19:12:16 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:29 2003 Subject: [Lf] [Fwd: LF: DDS Sources in receivers] Message-ID: <396F9040.8F7ABAC5@bellatlantic.net> Talbot Andrew wrote: > A few EMails to this reflector have recently been knocking the use of > DDS sources in receivers. Well the facts are as follows : > > A DDS does indeed generate spurious products, but these are precisely > characterisable and at a level defined by the chip manufacturer. Apart > from image and harmonics, they are a function of the DDS process and NOT > SUBJECT to poor layout construction etc whereas a phase locked loop > synthesizer is unbelievably sensitive to noise etc in the control > circuitry caused by poor design. Furthermore, the spurs are usually > well away from the wanted frequency so properly applied filtering will > eliminate any possible spurious responses. > > Quantisation noise, cited on this reflector as being a performance > limiter is a function of A/D resolution and specificed in the data sheet > and is the only jitter present as mentioned by a previous posting. > This is simple DSP theory and defined precisely by maths plus any > degradation caused by manufacturers implementation, and Analog Devices > are a chip maker who know what they are doing in the DSP world. There > is no magical 'other source' of signal degradations caused by the > digital process. > In the case of the AD9850 spurious products and quatisation are at least > 60dB down with the specified output filter. Even without the proper > filter, the main products present are then the image response at > Fclock - Fout plus harmonics, usually well removed from the wanted > freq when at LF. In some cases these 'spurious' products can be treated > as the wanted ones and extracted by bandpass filtering instead, giving > access to DDS derived accuracy and phase noise at quite high VHF > frequencies. > > Phase noise is excellent on a DDS, in fact, it is equal to that of the > clock divided down by the synth ratio. So if the clock is generated by > something like a 100 MHz butler crystal oscillator as used by many > microwavers, that is probably the best phase noise that will EVER be > achievable at LF to HF, several orders better than a good LC osc and > making the spectrum of a PLL synth look like wading through a cornfield. > > Phase noise is a vital parameter for LF receivers as it directly sets > the minimum theoretical bandwidth of a signal. Conversely, for a PLL > phase noise is never that good unless a very high Q narrow bandwidth VCO > is used. In this case it becomes a specific design useful only for its > one design purpose. A common DDS design will serve as optimum for the > entire output range > > Any one who advocates using a PLL just to 'clean up' a DDS is asking for > the worst of all worlds. A valid reason for doing this however, is if > the DDS is used as a reference for a microwave synth, which then > multiplies the high resolution signal to the microwave range whilst > keeping a high reference comparison frequency to minimise phase noise. > For example, a 3 GHz synthesizer using a 50MHz DDS derived reference > will have steps of less than 1 Hz and a phase noise at bandwidths within > its loop bandwidth - ie. close in - probably acceptable for SSB use. > > Andy G4JNT > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution, > or any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From fgentges at mindspring.com Sat Jul 15 16:17:03 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:29 2003 Subject: [Lf] Naval Academy Ham Radio Club Message-ID: <3970B8AF.45D5C95C@mindspring.com> Looks like the Naval Academy is going to close the ham station there. Looks like the towers at NSS were just the start. Frank K0BRA K3for wrote: > > Help! > > I am looking for other Naval Academy graduates or US Naval personnel who can > assist me in saving the amateur radio club at USNA. > > I have been the officer rep for the past 2.5 years, but a decision was just > made in the past 48 hours (over the summer while the mids are conveniently out > at summer training or on leave) without notice or discussion, to disestablish > the station W3ADO (also Navy MARS station NNN0NNN). Perceived lack of > participation, lack of knowledge of our various missions and accomplishments > ("oh, ham radio is dead..."), and funding probably played a role. > > Mailing address for support letters: > Captain Sam Locklear, USN > Commandant of Midshipmen > 101 Buchanan Road > US Naval Academy > Annapolis, MD 21402 > > cc me at: > Ryan "Skip" Johnson > 510 Norton Lane > Arnold, MD 21012 > k3for@aol.com > if you can > > Or if you can't write a letter, please email me something and I will forward it > to the Deputy Commandant by email. > > Thank you ! I only hope its not too late -- I have to run down there and see > if they've thrown out the gear already... > > 73's > Skip/K3FOR > Navy MARS NNN0PEK > Annapolis Frank -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From fgentges at mindspring.com Fri Jul 14 23:54:48 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:30 2003 Subject: [Lf] [Fwd: Help - Naval Academy ham radio club in danger] Message-ID: <396FD278.F33C9C6C@mindspring.com> Looks like the Naval Academy is going to close the ham station there. Looks like the towers at NSS were just the start. Frank K0BRA K3for wrote: > > Help! > > I am looking for other Naval Academy graduates or US Naval personnel who can > assist me in saving the amateur radio club at USNA. > > I have been the officer rep for the past 2.5 years, but a decision was just > made in the past 48 hours (over the summer while the mids are conveniently out > at summer training or on leave) without notice or discussion, to disestablish > the station W3ADO (also Navy MARS station NNN0NNN). Perceived lack of > participation, lack of knowledge of our various missions and accomplishments > ("oh, ham radio is dead..."), and funding probably played a role. > > Mailing address for support letters: > Captain Sam Locklear, USN > Commandant of Midshipmen > 101 Buchanan Road > US Naval Academy > Annapolis, MD 21402 > > cc me at: > Ryan "Skip" Johnson > 510 Norton Lane > Arnold, MD 21012 > k3for@aol.com > if you can > > Or if you can't write a letter, please email me something and I will forward it > to the Deputy Commandant by email. > > Thank you ! I only hope its not too late -- I have to run down there and see > if they've thrown out the gear already... > > 73's > Skip/K3FOR > Navy MARS NNN0PEK > Annapolis -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From fgentges at mindspring.com Sat Jul 15 22:40:49 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:30 2003 Subject: [Lf] Solar Storm Message-ID: <397112A1.49787F27@mindspring.com> It is now 0135Z July 16. That is 9:30 pm July 15. There is a major solar storm impacting earth. The flux has been off-scale for the past three hours. You can see this at . Additional information is at . I have not seen any unusual changes at LF. There is lots of power line noise and some sferics. HF is pretty bad and most signals are way down. If the clouds clear a bit there could be a real show of the Northern Lights. Frank -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From akestelo at bellatlantic.net Sun Jul 16 18:51:01 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:30 2003 Subject: [Lf] LF: Loading coils.] Message-ID: <39722E45.414A094A@bellatlantic.net> Dave wrote: > Dear all. > > It was a sunny afternoon ( honestly! ) so I thought I would compare a few > loading coils on 136. Theory states that most losses are in the earth system > and losses in the coil would have to be pretty big to make a difference. > > I tried three coils: > My usual coil 380mm dia 500mm high 4mm o.d. wire > My /P coil 200mm dia 210mm high 1.25mm o.d. wire > Ex Decca 810mm dia 210mm high 4mm o.d. litz wire > > Guess what? > No difference at all! > At the test power, about 800W, I got exactly the same aerial current in each > case. > > So there..... > > 73. Dave G3YXM. From akestelo at bellatlantic.net Mon Jul 17 00:03:53 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:30 2003 Subject: [Lf] [Fwd: LF: Loading coils.] Message-ID: <39727799.20BA1C9B@bellatlantic.net> vernall wrote: > Dave wrote: > > > > Dear all. > > > > It was a sunny afternoon ( honestly! ) so I thought I would compare a few > > loading coils on 136. Theory states that most losses are in the earth system > > and losses in the coil would have to be pretty big to make a difference. > > > > I tried three coils: > > My usual coil 380mm dia 500mm high 4mm o.d. wire > > My /P coil 200mm dia 210mm high 1.25mm o.d. wire > > Ex Decca 810mm dia 210mm high 4mm o.d. litz wire > > > > Guess what? > > No difference at all! > > At the test power, about 800W, I got exactly the same aerial current in each > > case. > > > > So there..... > > > > 73. Dave G3YXM. > > This is a fairly convincing result that you have high ground loss, that > swamps observation of the differences in coil loss. > > Coil loss could be assessed by separately checking them, resonated with > polystyrene capacitors roughly equal to your top loading capacitance, > and observing the 3 dB bandwidth. The dynamic resistance can then be > calculated. > > However, working on lowering the ground loss(es) would seem to be a more > rewarding pursuit. > > 73, Bob ZL2CA From akestelo at bellatlantic.net Mon Jul 17 00:04:14 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:30 2003 Subject: [Lf] [Fwd: LF: A small question of size] Message-ID: <397277AD.D10B45C8@bellatlantic.net> vernall wrote: > john sexton wrote: > > > > Hi Bob, > > > > The Radiation Resistance is proportional to the square of the area of the > > loop, and therefore the fourth power of the diameter. So 30 feet diameter > > compared with 20 feet diameter increases Rr by a factor of just over 5. > > > > John, G4CNN > > That is of most interest for a transmitting loop. For a receiving > situation, the radiation resistance is not the paramount parameter. At > LF there is significant external noise (QRN) so the received signal > quality can never be better than the signal to QRN ratio. The receiving > loop needs to be big enough so that QRN swamps thermal noise in the > receiver or pre-amplifier. I would think that 2 metres diameter would > be adequate for a loop receiving antenna for any LF band (noting that > QRN power increases with decreasing frequency). If there is local QRM, > then a smaller loop can be sited for best isolation from the QRM and > outperform a larger loop (that has a larger near field). > > So bigger is not necessarily better for an LF receiving loop. > > 73, Bob From akestelo at bellatlantic.net Mon Jul 17 09:20:11 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:31 2003 Subject: [Lf] [Fwd: LF: DDS Sources in receivers] Message-ID: <3972F9FB.1AB4CA28@bellatlantic.net> Talbot Andrew wrote: > Unfortunately, the output of the numerical controlled oscillator has to > be turned into a real signal, and as it represents a quantised series of > angles, a sine ROM must be used to generate a sinewave. Any other > mapping would generate an unpredictable set of non harmonically related > spurii. A DDS output unfiltered is not a square wave. The quality / > resolution in this ROM sets the spurious output level and for the AD9850 > this is sufficient to meet the specified 60dBc output purity spec. > To generate a squarewave, you need to take the filterd sine output and > apply it to a comparator. The AD9850 chip includes such a comparator, > capable operating up to beyond 40MHz > > The 9850 PCBs are now being supplied by HF Instruments ?8.00 for the > PCB, ?40 for one with the DDS chip pre-mounted with only a few other > components to install. Phone Chris Tew or Paul Phillips on 01420 > 590000 (+44 1420 590000) to order. Designs and software using this > module will follow from time to time. > > I am about to make a start on a custom LF receiver based on a 455kHz IF > and surplus 300Hz mechanical filter, all locked to a master reference > oscillator. A DDS will be used as the Local Oscillator (properly > filtered of course !) and possibly another one for the BFO although this > is not so essential if a constant output tone of 1kHz is deemed > satisfactory > > Andy G4JNT > > > ---------- > > From: Rik Strobbe[SMTP:rik.strobbe@fys.kuleuven.ac.be] > > Reply To: rsgb_lf_group@blacksheep.org > > Sent: 2000-07-17 10:47 > > To: rsgb_lf_group@blacksheep.org > > Subject: Re: LF: DDS Sources in receivers > > > > At 21:44 14/07/00 +0200, DJ5HG wrote: > > >... > > >In my previous mail I pointed out, that the spurs generated by a DDS > > >are due to an imprecise implementation of the sine function. This > > >imprecision is a result of a compromise between the diverging goals, > > >speed and precision. > > >... > > > > I followed the discussion about DDS signal sources in receivers 'with > > one > > eye', so maybe I missed something. > > But is it nessecary to create a sine wave ? > > At LF & VLF analog switches can be used to make 'state of the art' > > mixers. > > Analog switches with an on-resistance as low as a few Ohm and a > > switching > > time as fast as a few nannoseconds are cheap an easily available. > > These analog switches have to be driven by a square wave, maybe this > > can > > simplify the DDS design. > > > > 73, Rik ON7YD > > > > From akestelo at bellatlantic.net Mon Jul 17 09:21:42 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:31 2003 Subject: [Lf] Loading coils.] Message-ID: <3972FA55.5D6BE36D@bellatlantic.net> Rik Strobbe wrote: > Hello Bob & Dave, > > I just tried to 'reconstruct' Daves experiment on paper. > I assumed that : > - the 'bad' /P coil had a Q of 370 (refernce : my loading coil is made of > 1mm solid Cu wire and has a Q of 350) > - the 'good' Decca coil has a Q of 600 > - an groundloss of 50 Ohm (average ground) > - an antenna capacitance of 500pF. > For 137kHz you will need a coil of 2.7mH (XL = 2.3 kOhm). For the /P coil > (Q of 370) the loss will be 6.2 Ohm, for the decca coil (Q of 600) the loss > will be 3.8 Ohm. > So the total loss will be 56.2 Ohm for the /P coil and 53.8 Ohm for the > decca coil. > With 800W this means an antennacurrent of 3.77A for the/P coil and 3.85A > for the decca coil. This is a difference of only 2% (or less than 0.2dB). A > difference that hardly will be noticed on the band and with a lot of RF > current meters you might need a sharp eye to see a significant difference. > > 73, Rik ON7YD > > At 10:36 17/07/00 +1200, ZL2CA wrote: > >Dave wrote: > >> > >> Dear all. > >> > >> It was a sunny afternoon ( honestly! ) so I thought I would compare a few > >> loading coils on 136. Theory states that most losses are in the earth > system > >> and losses in the coil would have to be pretty big to make a difference. > >> > >> I tried three coils: > >> My usual coil 380mm dia 500mm high 4mm o.d. wire > >> My /P coil 200mm dia 210mm high 1.25mm o.d. wire > >> Ex Decca 810mm dia 210mm high 4mm o.d. litz wire > >> > >> Guess what? > >> No difference at all! > >> At the test power, about 800W, I got exactly the same aerial current in > each > >> case. > >> > >> So there..... > >> > >> 73. Dave G3YXM. > > > >This is a fairly convincing result that you have high ground loss, that > >swamps observation of the differences in coil loss. > > > >Coil loss could be assessed by separately checking them, resonated with > >polystyrene capacitors roughly equal to your top loading capacitance, > >and observing the 3 dB bandwidth. The dynamic resistance can then be > >calculated. > > > >However, working on lowering the ground loss(es) would seem to be a more > >rewarding pursuit. > > > >73, Bob ZL2CA > > > > > > > > From akestelo at bellatlantic.net Mon Jul 17 09:28:24 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:31 2003 Subject: [Lf] [Fwd: LF: Ground Losses] Message-ID: <3972FBE8.69E95549@bellatlantic.net> Talbot Andrew wrote: > It would be interesting if we could compile a list of grounding systems > and their losses to see if their are any common factors related to loss. > To start the ball rolling, here is a description of the 'JNT system: > > A garden 13m long by 6m wide, house at one end, soil is heavy clay. One > copper wire buried the length of the garden running directly underneath > the antenn top loading wire. Copper earth stakes 1m long at each end of > this. At the the antenna loading coil half way along and near one side > of the boundary, three other radials radiate out from this over a half > circle across the garden to corners and far side, with lengths from 4 to > 7m each terminated in a grounding rod. One end of the long run and one > radial are also connected back to the house earthing which is on a PME > system. (I know this is naughty, but used 6mm^2 cable, twice, to meet > wiring regulations and fault current limits). Radial wires a roughly > equal mixture of bare copper and PVC covered > > At 137kHz the gound losses are measured at 70 ohms with about 10% > variation due to dry/wet weather - which as far as I can see looks quite > good compared with some of the figures mentioned in the past. Perhaps > due to the good ground conductivity. > 73kHz the loss resistance increases to 120 - 180 ohms (depending on > weather) > > The large change between bands make me suspect that a substantial > portion of the losses is caused by obstructions near the antenna > terminating the reactive or displacement current which is obviously much > more at 73kHz than it is at 137kHz. > ------------------------- > As an interesting aside, I disconnected the PME to mains neutral bond > wire and measured the resistance (using a 12 Volt source) between my > earthing system firmly bonded to all metalwork in the house with the > radials / rods, and the electricity boards PME Earth. The only ground > connected metallic pipework in the house is a short gas pipe running in > a concrete floor so I know all connections from the house metalwork to > Earth are down to me. The DC resistance was constantly in the 2.5 to 3 > ohms region before the Elec board rewired the street to replace their > unreliable aluminium cable that caused power cuts 1 - 2 times per year. > I haven't measured resistance since, but hopefully it will be lower > still now. > > While this rewiring was underway, I had the opportunity to see just how > the Multiple bit of PME was implemented. At every cable junction for > each pair of houses, a 10mm^2 wire was brought out and connected to an > earth stake. This process is repeated right back to the substation > which in my case is only 100m down the road. > > Andy G4JNT > > > ---------- > > From: Rik Strobbe[SMTP:rik.strobbe@fys.kuleuven.ac.be] > > Reply To: rsgb_lf_group@blacksheep.org > > Sent: 2000-07-17 11:49 > > To: rsgb_lf_group@blacksheep.org > > Subject: Re: LF: Loading coils. > > > > Hello Bob & Dave, > > > > I just tried to 'reconstruct' Daves experiment on paper. > > I assumed that : > > - the 'bad' /P coil had a Q of 370 (refernce : my loading coil is made > > of > > 1mm solid Cu wire and has a Q of 350) > > - the 'good' Decca coil has a Q of 600 > > - an groundloss of 50 Ohm (average ground) > > - an antenna capacitance of 500pF. > > For 137kHz you will need a coil of 2.7mH (XL = 2.3 kOhm). For the /P > > coil > > (Q of 370) the loss will be 6.2 Ohm, for the decca coil (Q of 600) the > > loss > > will be 3.8 Ohm. > > So the total loss will be 56.2 Ohm for the /P coil and 53.8 Ohm for > > the > > decca coil. > > With 800W this means an antennacurrent of 3.77A for the/P coil and > > 3.85A > > for the decca coil. This is a difference of only 2% (or less than > > 0.2dB). A > > difference that hardly will be noticed on the band and with a lot of > > RF > > current meters you might need a sharp eye to see a significant > > difference. > > > > 73, Rik ON7YD > > > > At 10:36 17/07/00 +1200, ZL2CA wrote: > > >Dave wrote: > > >> > > >> Dear all. > > >> > > >> It was a sunny afternoon ( honestly! ) so I thought I would compare > > a few > > >> loading coils on 136. Theory states that most losses are in the > > earth > > system > > >> and losses in the coil would have to be pretty big to make a > > difference. > > >> > > >> I tried three coils: > > >> My usual coil 380mm dia 500mm high 4mm o.d. wire > > >> My /P coil 200mm dia 210mm high 1.25mm o.d. wire > > >> Ex Decca 810mm dia 210mm high 4mm o.d. litz wire > > >> > > >> Guess what? > > >> No difference at all! > > >> At the test power, about 800W, I got exactly the same aerial > > current in > > each > > >> case. > > >> > > >> So there..... > > >> > > >> 73. Dave G3YXM. > > > > > >This is a fairly convincing result that you have high ground loss, > > that > > >swamps observation of the differences in coil loss. > > > > > >Coil loss could be assessed by separately checking them, resonated > > with > > >polystyrene capacitors roughly equal to your top loading capacitance, > > >and observing the 3 dB bandwidth. The dynamic resistance can then be > > >calculated. > > > > > >However, working on lowering the ground loss(es) would seem to be a > > more > > >rewarding pursuit. > > > > > >73, Bob ZL2CA > > > > > > > > > > > > > > > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution, > or any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From akestelo at bellatlantic.net Tue Jul 18 08:39:19 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:32 2003 Subject: [Lf] [Fwd: LF: RE DDS Sources in receivers] Message-ID: <397441E7.928E1E8@bellatlantic.net> Talbot Andrew wrote: > Yes, but a 100 Hz step on a single loop 136MHz PLL will mean that you > will need a very long loop time constant - of the order of a second or > more. Phase noise on the VCO outside this bandwidth will then remain > uncorrected, and will appear divided down in bandwidth by 1000. You > will also be unlikely to filter out the 100 Hz sidebands. When the > signal is divided down, then the classic FM situation will appear where > the FM sidebands ar still at the same spacing but at different levels - > ie. you will still have 100 / 200 / 300 Hz sidebands but at lower > levels. A double loop synth would help but the complexity involved > here sureley means looking at other techniques. > I suspect that the residual spurii will be worse than the 60 - 70dBc for > a DDS design and spaced much wider. > > As a test last night, I mixed the output of my DDS LF generator set to > generate 59.8kHz, (DDS clocked at 5MHz) with an off air MSF signal at > 60kHz. The resulting 200 Hz output was low pass filtered and fed to > the soundcard and monitored with Gram and also on similar software for > the 56002EVm - EVMSPEC.. The only sidebands visible were those caused > by the switching of the MSF carrier, no sign of the jitter mentioned by > Klaus, DJ5HG. But, as Spectran only gives about 70dB dynamic range > anyway. EVMSPEC can just about cope with 80dB dynamic range, and again > there was again nothing obvious > The next test is to take two DDS sources, mix them together and try to > generate this 'noise' that is supposed to be present. I have certainly > never seen anything in the past that is worse than the 60dBc or whatever > specified. > > About 10 years ago I witnessed some tests being done on an early > (Plessey I think) GaAs logic based DDS clocked at UHF. The D/A in that > was low resolution, probably an 8 bit flash design, and sprogs were > many. But they were as predicted, 30 - 40dB levels typically and at > frequencies that could be calculated in advance. The wanted output was > a clean carrier. This design was soon superceeded by the more modern > ones around now. I note that my IC746 has three DDS's in it, but > interestingly each one has a separate discrete R-2R ladder chain for its > D/A, the switches being inside the (FPGA ?) special function chips > making up the logic board. > > I still maintain that a DDS is one of the cleanest in terms of phase > noise, and certainly the most flexible frequency source around these > days. The cleanest frequency source achievable, ever, will likely > always be a straight well designed crystal oscillator in a Butler > configuration. > > What are the implications of 60dBc sideband / phase noise anyway ? They > are only going to matter if an INBAND signal is 60dB up on the wanted > one, and isn't that quite likely to give problems elsewhere in the > processing chain ? > > Andy G4JNT > > > I was thinking of an alternative route, by using a classic PLL in the > > VHF > > range and devide it down to LF. A PLL system working on 136MHz in > > 100Hz > > steps can be devided by 1000, giving you 0.1Hz steps on 136kHz. > > Dividing by > > 1000 will also result in a significant phasenoise reduction. > > > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution, > or any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From akestelo at bellatlantic.net Tue Jul 18 08:41:22 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:32 2003 Subject: [Lf] [Fwd: LF: RE DDS Sources in receivers] Message-ID: <39744262.38FDF1FE@bellatlantic.net> Klaus von der Heide wrote: > Hello all, hello Andy, > > Andy wrote: > > As a test last night, I mixed the output of my DDS LF generator set to > > generate 59.8kHz, (DDS clocked at 5MHz) with an off air MSF signal at > > 60kHz. The resulting 200 Hz output was low pass filtered and fed to > > the soundcard and monitored with Gram and also on similar software for > > the 56002EVm - EVMSPEC.. The only sidebands visible were those caused > > by the switching of the MSF carrier, no sign of the jitter mentioned by > > Klaus, DJ5HG. > > Fine! Obviously this chip is designed to that accuracy. Sorry, at the > moment I have no time to measure the AD9850 down to 120 dB with my > DSP56002EVM. > (At that resolution you can see funny things. Some months ago I found > spurs +-50 Hz and +-100 Hz from any analog carrier fed into the EVM. > They are due to an amplitude modulation of the ADC by the supply!) > > > I still maintain that a DDS is one of the cleanest in terms of phase > > noise, and certainly the most flexible frequency source around these > > days. > > Yes, and the spurs are not an intrinsic DDS-problem, but only a > problem introduced by simplification. > > > What are the implications of 60dBc sideband / phase noise anyway ? They > > are only going to matter if an INBAND signal is 60dB up on the wanted > > one, and isn't that quite likely to give problems elsewhere in the > > processing chain ? > > If your input filter stops all OUTBAND signals in the entire spectrum > sufficiently, then only the INBAND problem will be present. May be, > that's not a real problem. > > If this processing chain is digital at say 24 bits, the processing > chain does not generate further problems. > > 73 de Klaus, DJ5HG From akestelo at bellatlantic.net Tue Jul 18 08:43:07 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:32 2003 Subject: [Lf] [Fwd: LF: A small question of size] Message-ID: <397442CB.31B5FC07@bellatlantic.net> vernall wrote: > john sexton wrote: > > > > Hi Bob, > > > > I am glad you pointed that out, so much for theoretical formulae, I was just > > about to embark on a much larger receiving loop. My current one is about 1 > > metre in diameter. It outperforms the vertical, just because the noise is so > > much less. However I have noticed that when I connect the vertical to the > > Tx, there appears to be a lot of coupling between the two antennas, and the > > noise level goes up from the loop. > > > > Vy 73, John, G4CNN > > Similar at my QTH. For LF receiving I usually use an active whip sited > at the back fence of my property (for maximum separation from houses). > When my nearby toploaded (transmitting) vertical is connected the > neighbourhood noise rises about 20 dB. The neighbourhood noise is > mostly clicks, pops and PSU hash that I assume is transported on the > power mains. On receive, I not only have the transmitter off, but I > also need to "float" the transmitting antenna. This is an example of > the larger near field of the larger vertical leading to generally worse > results for receiving than using a smaller but well-sited antenna. > > Straying a little off the topic: it is also important to have a well > isolated power supply and common mode choke on every connection to a > remote receiving antenna, otherwise the dreaded mains noise will sneak > in to the system. Balanced RF feeders with transformer coupling at each > end is probably the simplest technique that can deliver good results. > > 73, Bob ZL2CA From akestelo at bellatlantic.net Tue Jul 18 08:42:25 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:32 2003 Subject: [Lf] [Fwd: LF: DDS Sources in receivers] Message-ID: <397442A0.67D5E63C@bellatlantic.net> Klaus von der Heide wrote: > Andy, G4JNT wrote: > > > Unfortunately, the output of the numerical controlled oscillator has to > > be turned into a real signal, and as it represents a quantised series of > > angles, a sine ROM must be used to generate a sinewave. Any other > > mapping would generate an unpredictable set of non harmonically related > > spurii. > > DDS means direct digital synthesis, whatever you choose to generate > the function (sine in most cases) digitally. Normally a phase > accumulator pa of 32 bits is incremented by a constant phase step at > the sample rate. The sine phase then is p = pa*2*pi/2^32. > sin(p) can be calculated from this phase at any accuracy you want, > by rational Chebyshev-approximation for example as it is done on a > normal computer. Spurs occur by imprecise sine implementation. The > usual way is to use a sine-ROM that is addressed by the first 8 bits > of pa. If the contents of this ROM is directly used as output, that's > wrong when the last 24 bits of pa do not vanish. In the case of > 8 address bits, i.e. a ROM of 256 sine values, the amplitude-error is > up to 2% which is worse than a quantization by only 6 bits. That is > the error, you mentioned: The phase, that originally is quantized in > 32 bits is again quantized into 8 bits, which produces an amplitude > error of up to 2%. Yes, you are right: so it is, if you do so. > If on the other hand the sine is computed at the correct phase of > 32 bits, this error does not occur. In my last mail I showed the > Taylor-series which is nice for sine generation. Using that series > with the same sine table of 256 values, the amplitude error drops > down to 0.000000005, which is more than you need. > > Because of the importance of the DDS I made two impressive programs > for demonstration in my lectures: Both are DDS-realizations with > two parameters: (1) Length of the sine table; (2) number of bits > to represent the sine values in the table. > The first program is in MATLAB. It shows the spectrum with all spurs, > the second is an audio demonstration programmed on the DSP56002EVM. > Using simply a small sine table without interpolation sounds like > many birds in the background. Even if a sine table of only 16 entries > is used (4 address bits) no spurs can be heard, when the Taylor- > series works (then spurs < -60 dB). > > > A DDS output unfiltered is not a square wave. The quality / > > resolution in this ROM sets the spurious output level and for the AD9850 > > this is sufficient to meet the specified 60dBc output purity spec. > > To generate a squarewave, you need to take the filterd sine output and > > apply it to a comparator. The AD9850 chip includes such a comparator, > > capable operating up to beyond 40MHz > > That is a very useful feature of this chip. I use two AD9850 in this > digital mode combined by digital logic to generate square waves with > edges that can be adjusted in extreme fine steps by program. > > > I am about to make a start on a custom LF receiver based on a 455kHz IF > > and surplus 300Hz mechanical filter, all locked to a master reference > > oscillator. A DDS will be used as the Local Oscillator (properly > > filtered of course !) and possibly another one for the BFO although this > > is not so essential if a constant output tone of 1kHz is deemed > > satisfactory > > As the previous discussion showed, a filtering of the DDS-signal does > not help against the many spurs very near to the sine frequency. It > is better to downconvert to AF by say 128 kHz and to do the tuning > and filtering digitally by sound card or DSP. Or sample the 136 kHz > directly and send the result via the USB-Port to the PC. The latter > really would be a revolution in amateur radio. > > But, if you plan your original structure, you possibly should think > about one more AD9850, that can be programmed to generate any sample > clock synchronously to the other frequencies. > > Now I have to leave this reflector for six weeks of holiday. > Have nice discussions and luck on LF! > > 73 de Klaus, DJ5HG From akestelo at bellatlantic.net Tue Jul 18 19:08:17 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:33 2003 Subject: [Lf] [Fwd: [Lowfer] Update on XMGR] Message-ID: <3974D551.CAAB1340@bellatlantic.net> Impressive stuff Andre' *************************** les@highnoonfilm.com wrote: > Complete details on the XMGR update have been posted on our website: > > http://www.highnoonfilm.com/xmgr > > In summary, I've completed the construction of the new antenna. It is a > "flattop" vertical very > similar to the type used by NDB beacons. The vertical section is up to 40 > feet and the tophat > runs 70 feet in the horizontal direction. > > The transmitter and loading coil are mounted in a weatherproof enclosure > mounted above > an 80 foot radius elevated counterpoise ground system. I am installing a > total of 32 radials, > most of which will be terminated on the chain link fence that surrounds the > backyard. This > fence is grounded and bonded to several 10 foot copper rods at various > points. > > The beacon has also moved to 186.404 Khz. Unless there is a good reason to > move, > we'll stay at this frequency for the coming season. (This is the "old" > frequency for the > beacon when it was on the air ten years ago) > > We have also posted a listing of lowfers in the Central and Eastern US. We > are starting to > list "indicators" of NDB beacons that are nearby these lowfer beacons to > check propagation. > For instance, NDB beacon "BEQ" is a 25 watt beacon on 368Khz, located 4 > miles from my > QTH. If you can't hear this 25 watt beacon on any given night, my 1 watt > signal is not likely to > make the trip (at least not on CW) > > The next phase involves hooking it up the LF analyzer and getting some hard > data on the antenna. > After that we'll be installing the new CW/BPSK transmitter. Whew! > > Please do send in your own "indicator" information so that I can post that > to the listing. Also, we > need video tapes and/or photographs for the documentary. Bill "TEXAS" shot > over 30 minutes > of footage of his set-up that promises to be incredible! Can't wait to see > more from the > rest of you! > > Les Rayburn, N1LF (XMGR) > 4919 Cox Cove > Helena, AL 35080 > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Wed Jul 19 11:42:43 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:33 2003 Subject: [Lf] RF gain IC Message-ID: <3975BE62.C501D4F0@bellatlantic.net> Rik Strobbe wrote: > At 14:24 19/07/00 +0100, G4JNT wrote: > >For some time I have been searching for a decent modern IC for the gain > >controlled IF amplification function in a linear (SSB etc.) receiver but > >have had no luck finding what I'm looking for. > > Hi Andy, > > I've used a 8-bit DAC (digital analog convertor) as 'digital controlled > amplifier'. > Basicaly you replace the DAC reference voltage by the AC input signal and > get the amplified (or attenuated) signal at the DAC output. Gain is > controlled by the digital input of the DAC. Dynamic range depends on the > number of bits (of the digital input), a 8-bit DAC gives about 48dB, a > 12-bit 72dB and a 16-bit DAC even a respectable 96dB (if you manage to get > the proper PCB layout). > > As I only needed 40dB dynamic range I used a cheap DAC-08 from Analog Devices. > It worked fine at 240kHz, I belive that the application note gave a 1MHz > limit. > But more recent (faster) DAC's might be good for higher frequencies. > > I believe I have the application note still somewhere (as PDF file), if you > want I can search it and mail it to you. > > 73, Rik ON7YD From akestelo at bellatlantic.net Thu Jul 20 11:17:07 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:33 2003 Subject: [Lf] RF ICs Message-ID: <397709E2.B4348F23@bellatlantic.net> Talbot Andrew wrote: > Thanks to everyone who replied re RF amplifier ICs > Several suggested the Analog Devices AD600 - AD603 family so obtained > the data sheets for these........ > > They are a receiver designers dream !! > > AD600 has TWO 40dB gain stages, each with an accurately calibrated > voltage driven attenuator giving a control range of 40dB. So in total 0 > - 80dB gain using both stages. Only snag is the device is ?22 (+ VAT) > from Farnell. Its also available in standard DIL packaging as well as > SMT - makes breadboarding a bit easier (at low frequencies anyway) > > 80dB is probably a bit too much gain, so the AD603 which is broadly > similar to one of the '600 stages, with 50dB gain max at below 9MHz and > again 40dB of range will probably do, along with one other switchable > amp in the RF chain. This device is ony ?9 from Farnell and in an 8 > PIN package too. > > I like Analog Devices chips - they have a huge range of useful, well > thought out, .... analogue devices ! > > Andy G4JNT > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution,o > r any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From akestelo at bellatlantic.net Thu Jul 20 20:31:10 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:33 2003 Subject: [Lf] Some info on inexpensive approach to RX] Message-ID: <39778BBE.70B78D99@bellatlantic.net> Bob Duckworth wrote: > While looking for some info on the HP 3586B selective level meter > that is a mainstay here for bench and VLF,L, MF work, I ran across a nice > description of the utility of these things. > Looking around www I see these for $200 to $850 > A bargain high end RX! > > http://espresso.ts.uvic.ca/fsvm.htm > > and some specs on the HP > > http://pmtmde.redstone.army.mil/temod/4-1-21.htm > > -bob > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Fri Jul 21 18:37:07 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:33 2003 Subject: [Lf] Re: Ground Losses] Message-ID: <3978C283.6F13B090@bellatlantic.net> Peter Dodd wrote: > I measured the impedance and loss resistance of my antenna system > (as described by PA0SE) by inserting the 3-M > impedance bridge between the bottom end of the loading coil and the earth > connection. The results were as follows: > > Results +/-Errors > Freq MHz Res jX Res jX > ---------------------------------------- > .1364 37.9 - 29.4 2 2.1 > .1366 37.4 - 22.8 4.6 5.3 > .1368 33.5 - 22.2 5.1 5.7 > .1370 33.4 - 17.3 5.8 7.4 > .1372 35.6 - 8.8 2.8 3.5 > .1374 36.4 -0 1 1.7 2 > .1376 36.9 +0 5 1.1 1.3 > .1378 36.5 + 13.3 1 1.3 > .1380 38.1 + 21 1.1 1.8 > > The total resistance component is around 37.5ohms. The 3-M system > indicates probable errors on some readings and the 33ohm readings are ignored. > > I tried to measure coil Q, as described by Dick, > > > The loss resistance of the loading coil was determined by measuring its > >unloaded Q. The coil is resonated to 137 kHz with a good quality variable > >capacitor in parallel; a signal generator excites the coil via a one turn > >link that is kept at some distance from the coil; the probe of a sensitive > >selective level meter is held in the vicinity of the coil (both measures to > >avoid loading the coil) and the bandwidth B in kHz between the > >-3dB frequencies measured. Than Q = 137/B. > > My coil is made up of two coils, one commercial 300uH variometer and > a 2100uH fixed coil. The best Q obtainable was 142, which gives a > resistance of around 13ohms. I had some problems connecting the > signal generator and the level meter, as described above. If the > coupling was too loose there was direct pick up and I had to increase > the coupling to the coil. > > This implies a ground resistance at 137kHz of around 25ohms, which > makes this a good LF QTH, something I have known all along. > > The ground comprises a 2.5m layer of clay on sand and shingle. The > station is located 400m from the sea high water line. The ground > connection comprises a 2m long copper pipe in the ground close to the > loading coil. I also have a 10m square wire netting ground on the > surface. The maximum current is 3.5amps regardless of which earth is > used. Connecting both grounds together does not increase the current. > The next experiment is to try the Decca loading coil. > > Is it possible to get some indication of Q of the antenna system from > changes in reactance relative to frequency given above? > > > > -- > Regards, Peter, G3LDO > > From akestelo at bellatlantic.net Fri Jul 21 18:37:53 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:34 2003 Subject: [Lf] [Fwd: LF: Article on DDS VFO's] Message-ID: <3978C2B1.F43B1A8D@bellatlantic.net> Dick Rollema wrote: > To All from PA0SE On this reflector there has been quite a bit of > discussion on the merits of DDS VFO's. I therefore draw your attention > to an article in QEX of July/Aug 2000: Rick Peterson, WA6NUT: "A PLL > Spur Eliminator for DDS VFO's (Modern DDS systems can easily generate > RF signals - perhaps too many. This setup ensures pristine VFO > output". I leave it to the experts to judge the merits of this > article. 73, Dick, PA0SE From akestelo at bellatlantic.net Fri Jul 21 18:43:05 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:34 2003 Subject: [Lf] [Fwd: LF: Ground Systems & long wires Message-ID: <3978C3E8.2FCD4CA4@bellatlantic.net> Tom Boucher wrote: > Laurie asked for figures obtained by those with long wires. My 1100 ft > wire (when it was in the air, which it is not at present), gave me > approximately 4 amps of current with 400 watts. This indicates a loss > resistance of 25 ohms, quite low. The series loading coil at the feed > point is 0.8mH only. > > The wire was pretty much in a straight line except for the far 300 ft > which was bent back in a large loop about 200 ft diameter. > > The initial ground was mains earth plus a single 3 ft long half inch > copper pipe in the rather wet earth. There are a number of springs in > the garden so the soil is quite wet. The garden is fenced with 6 ft high > deer/rabbit fencing and this is now connected at one point to the > grounding system. The field containing most of the antenna is also > fenced but I have not as yet checked the electrical continuity. As far > as I remember, on connecting the fence, this gave a large, at least 50%, > increase in antenna current. > > Sorry about the feet and inches - like Tesco, I have reverted to > imperial measurements! > > 73, Tom G3OLB From akestelo at bellatlantic.net Fri Jul 21 18:52:27 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:34 2003 Subject: [Lf] [Fwd: LF: Ground Losses] Message-ID: <3978C61A.18CFB293@bellatlantic.net> James Moritz wrote: > Dear LF Group, > > Some more info for the 'ground' loss database: > > As a follow on to the Puckeridge antenna experiments of a couple > of months ago, I put up the same 42m long wire as I used for the > 'small' antenna at Puckeridge, in my back garden, and made some > measurements. The ground system in both cases was 4 x 1m > copper pipes, spread out 2m around the antenna downlead. > > The soil at my QTH is heavy clay, overlying chalk that seems to be > saturated with water (if you dig a hole, it will usually fill up). That at > Puckeridge seemed to be identical. The QTH is surrounded by > large trees on 3 sides, plus various houses and agricultural > buildings. At Puckeridge, the small antenna was put up in an open > field. > > At Puckeridge, the loss resistance was 25ohms. At home, this rose > to 40ohms. I compared this to my usual LF antenna, which has a > ground system using about 12 ground spikes spread all over the > garden, plus pipes and mains ground in the house - loss resistance > 50 ohms. > > You could argue that the low losses at Puckeridge might be due to > the ground spikes being close to the main antenna earth mat, > although to affect the loss resistance, only the ground very close > to the antenna will have much effect. However, the slightly better > efficiency of the small antenna compared to my usual antenna at > my home QTH strongly suggests that actual loss in the ground is > not the main factor - it was possible to position the 42m wire > further from the trees than the two wires of my usual antenna, so I > intend to experiment further along these lines. > > on 73kHz, the loss resistance of my usual antenna is about > 100ohms. I have not tried the 42m wire on 73k yet. > > Incidentally, after taking reduced antenna current into account, the > radiated signal from the 42m wire was about 3 - 4dB down > compared to at Puckeridge. If one adds the loss of efficiency, the > antenna radiates about 6dB less signal at home than it did at > Puckeridge. > > The loss resistance measurements are not of high precision, due > to the need to take into account the loss in the loading coil as well, > but the trend is definitely real. > > I have previously observed that the loss resistance rises as the > weather gets warmer, as has been reported by others, too. If > anything, the ground has been getting wetter as we go towards > summer, so this ought to bring ground losses down. > > Cheers, Jim Moritz > 73 de M0BMU From akestelo at bellatlantic.net Fri Jul 21 18:59:13 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:34 2003 Subject: [Lf] mesuring Ground Losses Message-ID: <3978C7B1.DA2B574E@bellatlantic.net> Dick Rollema wrote: > Larry and others, > > I measure the loss resistance Rtotal in the antenna system by inserting an > impedance bridge between the bottom end of the loading coil and the earth > connection. I have both a professional British Wayne Kerr admittance bridge > and a homemade RX-bridge with built-in noise source. Both produce identical > results: 30 ohms. But the latter is easier to use and therefore preferred. > > The loss resistance of the loading coil was determined by measuring its > unloaded Q. The coil is resonated to 137 kHz with a good quality variable > capacitor in parallel; a signal generator excites the coil via a one turn > link that is kept at some distance from the coil; the probe of a sensitive > selective level meter is held in the vicinity of the coil (both measures to > avoid loading the coil) and the bandwidth B in kHz between the > -3dB frequencies measured. Than Q = 137/B. > > The inductance L of the coil must be known and can be measured in several > ways. > Then Rcoil = (2 * pi * f * L) /Q; in my case 9 ohms > > Must be old hat to you ... > > As the loss resistance in the antenna wire is negligible (a few tenths of > ohm) I assume that the > earth resistance = Rtotal - Rcoil = 30 - 9 = 21 ohms. > > However part of it may be due to losses in the surrounding of the antenna > (not in trees, there are none near my antenna). Unfortunately it is > impossible to separate these from the real earth resistance. > > But I certainly would not classify my measurement of earth resistance as > "absolute". > > There is a classical way of measuring earth resistance using two auxiliary > electrodes. But it requires special test equipment, suitable for measuring > at 137 kHz to obtain a meaningful result. Unfortunately I lack the > equipment to perform such an "absolute" measurement. > > Even then the result might be misleading as Laurie has shown that the > "footprint" of the > antenna plays a role and that is not taken into account using the > three-electrode test. > > 73, Dick, PA0SE > > ----- Oorspronkelijk bericht ----- > Van: Larry Kayser > Aan: > Verzonden: woensdag 19 juli 2000 1:08 > Onderwerp: LF: Re: Re: Ground Losses > > > Dick: > > > > >The earth resistance at PA0SE varies somewhat with time of the > > >year. > > > > > >Today I measured the total resistance of the antenna system as 30 ohms. > > > > > >The loss resistance of the loading coil is 9 ohms. > > > > > >So for the earth resistance I find 21 ohms. > > > > > >The only earth here is the gas mains. > > > > > > Sometime when your feeling up to it I would sure like to know how you make > > absolute measurements of your antenna system. I have a great interest in > > this and would like to follow up further, again it is not an immediate > > interest - I doubt I could make any more significant changes to the > > processes to be used here in November in VO1 at this late date, but I sure > > would like to make absolute measurements of the antenna here as I get > ready > > to do BPSK trials over the North Atlantic next winter from here in Eastern > > Ontario. > > > > Larry > > VA3LK From akestelo at bellatlantic.net Fri Jul 21 19:16:42 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:34 2003 Subject: [Lf] Transmitting loops] Message-ID: <3978CBCA.C3BF91D5@bellatlantic.net> "Ashlock,William" wrote: > Due to a number of interesting transmitting loop discoveries over this week > I have decided to fully shut down WA @185.200 for a about a week to give me > time to figure out what is going on. I have constructed a 4'x4'x12 turn > transmitting test loop that surprisingly appears to match the prevailing > math for signal strength in the Lowfer band including area, current, and > number of turns with no apparent ground losses. Although my single turn > large loop has performed according to the math for a single turn, previous > experiments last fall indicated a decrease in signal with increased number > of turns. I am now thinking that this could have been due to inadequate > spacing of the turns (proximity effect) rather than due an increase in > currents induced in the ground. A couple of other discoveries with the test > loop are: > a) Far lower ground losses in terms of loop Q than originally assumed. I > have obtained a Q of 360 with the lower leg only 8" above and parallel to > the ground. > b) A 3db stronger signal in the far field when the loop is located over a > buried ground network rather than over bare ground. > > I would be interested in comparing notes with anyone that has experimented > with multi-turn transmitting loops at or near the Lowfer band. > > Bill WA > Andover, MA From akestelo at bellatlantic.net Fri Jul 21 23:41:35 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:35 2003 Subject: [Lf] MSK ? Message-ID: <397909DE.FF9203E1@bellatlantic.net> For a short introduction to MSK, look up http://www.cs.ucl.ac.uk/staff/S.Bhatti/D51-notes/node14.html Andre' N4ICK From akestelo at bellatlantic.net Sat Jul 22 19:53:59 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:35 2003 Subject: [Lf] QSO made - Canada on 136 Message-ID: <397A2607.A148119F@bellatlantic.net> Mitch Powell wrote: > Good day: > Poor to medium conditions, but at 1400 GMT - July 22, VA3LK and VE3OT > accomplished first 2-way QSO on 136 kHz - a first in Canada. > The distance was 431 kM (268 miles). Method was with QRSS, > using the sweep second hand to count the dots and dashes ! > > VA3LK - using IRF540 final ( 18V @ 4A) and with 270 ft tower. > VE3OT - G0MRF rig (at 200 watts) 50 foot marconi with 80 ft tophat. > > VA3LK 44:40N 76:25W and VE3OT 43N 81:15W (London, ON) > > Great relief to finally make it, and makes all efforts worthwhile. Will > progress now to improving antennas and "tweaking" the systems. > > Many thanks to all who advised, consulted and encouraged us with > this project. Larry is away for a few days holiday now and asked that I > generate this notice. > > 73 > Mitch VE3OT From akestelo at bellatlantic.net Sat Jul 22 19:58:36 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:35 2003 Subject: [Lf] Web bugs ? Message-ID: <397A271C.D8DDC0C2@bellatlantic.net> WEB BUGS THWART PRIVACY: WORSE THAN COOKIES by Dave Murphy, member@itrain.org Just yesterday I got excited about Microsoft's announcement that future versions of Internet Explorer would be able to cut out 3d-party cookies; a feature that's already included in the Opera web browser. Today, I'm blind sided by a new revelation that web bugs, 1-pixel transparent gif images, are being used by online advertisers to track you and me on the net: which sites, when we visit them, in what order we visit--all the items that are nobody's business by our own. Like cookies, web bugs are electronic tags that help Web sites and advertisers track visitors' whereabouts in cyberspace. But Web bugs are invisible on the page and are much smaller in file size, which makes them load quickly an unobtrusively. It's kind of like setting out a trip wire. The web bugs send a ping back to the advertiser's server every time we load a page that contains one, and the advertiser records that our computer just loaded that page. Well, I don't want to be tripped up, and I don't want to be trailed on the net. Web bugs can "talk" to existing cookies on a computer if they are both from the same Web site or advertising company, such as DoubleClick, which uses bugs and dominates the online advertising market. Ok, here's the real rub, More than a year ago, I reported that DoubleClick purchased Abacus Direct, the company that specializes in offline database marketing: magazine subscriptions, mailing lists, addresses, phone numbers, lots of personal identification information. Now, along comes DoubleClick again, fresh from losing an online privacy fight over invasive cookies, and it's using the web bugs to do it's dirty work again. The Web bugs do the tactical work, the cookies are running the strategic operations, and DoubleClick is waging war by matching up your online activities with Abacus Direct's mail order lists so your online and offline habits are synched. Now do you get the picture? From fgentges at mindspring.com Wed Jul 26 22:23:38 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:35 2003 Subject: [Lf] Lightning Detector Message-ID: <397F8F1A.AA31A303@mindspring.com> I ran across this web page on a lightning detector. I suspect it is related to our LF technology. Perhaps a pair of ferrite crossed loops with preamps inside that small plastic box. Maybe a good use of our LF gear during summer thunderstorms. Frank -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From akestelo at bellatlantic.net Thu Jul 27 21:27:58 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:35 2003 Subject: [Lf] [Fwd: LF: DDS Board details on web site and LF lowpower testing] Message-ID: <3980D38E.DFB0C64B@bellatlantic.net> Talbot Andrew wrote: > Somewhat belatedly, the HF-Instruments web site WWW.HF-INST.CO.UK does > now carry details of my AD9850 DDS Module. Apologies to those who went > there earlier and found nothing :-( It has been available for a couple > of weeks now, but the website didn't reflect this. I have MT-Hell and > DFCW software for this module free to anyone to builds it up. > > Now that the building work is finished, its time to return to radio > experiments again... > A few months ago, there was talk of controlled testing with very low > power signals to get some idea of the real capability of some of the > Spectran type software to pull signals out of the noise. This seems to > have gone quiet now - Summer weather and holidays perhaps, or has > interest waned. If anyone still wants to continue with this, I can put > out a beacon signal continuously (manned of course !) using a 6 Watt PA > which can be throttled back to nothing, and a small antenna. Slow-CW, > DFCW, MT-Hell or anything else on request is possible with a frequency > accuracy as precise as is needed (well, up to 10^-10 accuracy anyway) > > Andy G4JNT > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution, > or any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From akestelo at bellatlantic.net Thu Jul 27 21:37:12 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:35 2003 Subject: [Lf] LF Antenna Theory] Message-ID: <3980D5B8.3DC783C1@bellatlantic.net> LAWRENCE MAYHEAD wrote: > In his mail of 24/07, Dick PA0SE mentions the excellent QST article > by Rudy Severns. I have been studying this to see if there is any clue > to my "Footprint" theory.So far no luck, perhaps I am just not clever > enough.However I have recently extended one of my Top wires by 15m and > the total loss resistance is now 38 ohms.When I started I was getting > 120 ohms, so there definately seems to be a better return for effort > with wires in the air than from wires in the ground!73s to all, Laurie > G3AQC. From akestelo at bellatlantic.net Thu Jul 27 21:39:05 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:36 2003 Subject: [Lf] Ground Losses] Message-ID: <3980D629.28A62AAB@bellatlantic.net> Rik Strobbe wrote: > At 10:24 19/07/00 -0700, G4CNN wrote: > >I am interested to know how the guys with very low earth resistance have > >measured it. > > > >Using a 50V AC transformer secondary, I found my earth resistance to be only > >about 10 ohms, but at 136 kHz it appears to be quite different, much closer > >to 100 ohms. > 'Ground loss' is frequency dependent, the electric field penetrates deeper > into the ground at lower frequencies the losses increase when frequency > decreases. > But the 'system loss' on LF (and probably VLF) is not only ground loss. > Apart from the loss in the loading coil any object near the antenna will > contribe to the loss. Especially trees tend to act as lossy capacitors on > LF and can become a significant part of the system loss. > > 73, Rik ON7YD From akestelo at bellatlantic.net Thu Jul 27 21:43:16 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:36 2003 Subject: [Lf] Garmin GPS 12 Message-ID: <3980D724.DC8CD643@bellatlantic.net> Gang, Office Depot is getting rid of their stock of Garmin 12 GPS receivers. They are being sold at $49.95. I got the last one from Office Depot on Rt. 7 (near Tysons Corner) Virginia for $45 because it was demonstration model. It is loaded with 1999 software and has a spigot that allows for the use of various cables, to interface to a laptop, a 12volt source etc. 73 Andre' From akestelo at bellatlantic.net Thu Jul 27 23:24:44 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:36 2003 Subject: [Lf] Lightning Detector References: <397F8F1A.AA31A303@mindspring.com> Message-ID: <3980EEEC.3DE98AAC@bellatlantic.net> And he only wants $799 for that box... Andre Frank Gentges wrote: > I ran across this web page on a lightning detector. I suspect it is > related to our LF technology. Perhaps a pair of ferrite crossed loops > with preamps inside that small plastic box. Maybe a good use of our LF > gear during summer thunderstorms. > > > > Frank > > -- > Frank Gentges > K0BRA, ex AK4R, W3FGL > Check out our LF web page at > > _______________________________________________ > lf mailing list > lf@amrad.org > http://www.amrad.org/mailman/listinfo/lf From akestelo at bellatlantic.net Sat Jul 29 10:02:31 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:36 2003 Subject: [Lf] On managing a Radio-Shack... Message-ID: <3982D5E7.F79488C@bellatlantic.net> On Being Average by Tim Loughner "I am just a dude." That is what I say to myself when I look into my extra large bathroom mirror every morning as I try to flex my muscles which are buried under my blubbery "winter insulation." No matter how much I like to think I am God's gift to Man, I am shot down by my own self-actualization that I am simply: Average. Like most men, I enjoy the finer things in life: beer, home-theater, and a good steak. I won't kid anyone into thinking that I enjoy long talks, walks on the beach and romantic comedies, because I don't. I like my chili hot, my music loud, and sitting on my butt watching made for TV movies at two in the afternoon. Somewhere along the lines of man's evolution into the modern age, the pure and simple beauty of being your-lazy-good-for-nothing-self was degraded into a happy, touchy-feely, "I'm sorry" wuss of a man. One moment a guy got the chicks if he toted a gun and a 5 o'clock shadow, the next moment he is eating granola and drinking cappuccino's while watching Mad About You. Once men tuned up their muscle cars on Sunday afternoons while drinking half a case of beer, now they get dragged by their leashes to shopping malls and actually look like they might enjoy looking for that 40th pair of shoes with their wives. What has happened to embracing that which we men hold dear? Is it the Twilight Zone? Unsolved Mysteries? Invasion of the Body Snatchers? Only primetime TV provides the answers to the disturbing reality that man is slowly becoming... woman. After leaving a budding career as a surgical technologist, I chose to do what I like better - the Internet and sales. The Internet for obvious reasons like sitting on your butt for hours and sales for what I sell: electronics. Yes folks, by night I edit and publish The American Partisan, by day I manage a Radio Shack. I love working for the Shack. For starters, I get to play with lots of cool toys, get paid very well, and get a nice employee discount. But I am going to go a bit deeper, perhaps even a little sensitive here--you see, we save lives at Radio Shack. Malls are Hell on Earth for real men. Between the endless rows of women's clothing stores and the swarms of mall-rats spreading the Plague, Radio Shack is a virtual Mecca. There it stands, alone in the cold abyss like a life-raft in an endless sea of anti-man merchandising. Name another guy store in a mall... try it. Oh sure, you can find a Big 5 Sporting goods store or something along those lines. Many point to Eddie Bauer as a guys store, but what real man shops there? At the Shack, guys can breath the fresh, unscented air and talk about RF modulators and CB radios. We watch the game on satellite TV, play handheld poker games and listen to classic rock on 18 different radios. This is our version of crying on each other's shoulders about how much we hate being dragged by our testicles to the mall. In this small way guys are allowed to be just "dudes" as opposed to "wussies." Being a single guy, I enjoy the luxury of dirtying every dish in the house with cans of pork 'n' beans mixed with BBQ sauce. I can leave my smelly socks in the middle of the living room floor with only my roommate to add more. But most importantly, the toilet seats stays up! And why do we need to put toilet paper on the roll anyway? It's just fine on the bathroom counter. Men need to embrace this. Why? Because that is what we are, and those who won't 'fess up must have that whip cracking just bit extra hard or be a bit feminine themselves. I am not suggesting in becoming such a slob that your house becomes unsanitary. Yes guys, there is a time that you should clean the pubic hairs off the toilet bowl rim (or kitchen counter...) - do it sometime around the 15th of the month. Yes guys, you should wash dishes at some point - usually about the time that you run out of clean ones. Although I know it is tough, every chore has it's time and need. I may even create a "Man's Guide to Chores" in a future issue. We are not alone in our struggle for equal rights of the Man Lifestyle. TV programs like The Drew Carey Show and The Man Show has furthered the cause and has gained recognition for the problems facing the possible extinction of modern man as we know it. The NFL still exists in some form and beer is still legal. We have hope and there is still a faint light at the end of the tunnel. There is a fear of being ourselves. We must come out and say "YES! I am a man and I am proud! Accept me for who I am." We need to stand together as the entity of sloth. Overcome the fear, my friends, I will be there to guide you along the way. The Everyman's Must See Movie of the Week The X-Men... beautiful women, lots of action, stuff exploding, and beautiful women! Oh yeah, there is a message in there about equal rights or something. From akestelo at bellatlantic.net Sun Jul 30 12:42:36 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:37 2003 Subject: [Lf] [Fwd: [Lowfer] NDB Coils] Message-ID: <39844CEB.54EDC2F8@bellatlantic.net> Lyle Koehler wrote: > The coils you describe are probably efficient (I don't know about the > losses in the fiberglass cores), but don't have much inductance by > LowFER standards. A single layer solenoid of #10 wire, close wound on a > 3 inch diameter by 12 inch long coil, would have about 9 turns per inch > for a total of 108 turns. The inductance would be about 208 uH. Spacing > the turns by an amount equal to the wire diameter, which is a good rule > of thumb for obtaining maximum Q with solid wire, would reduce the > inductance to about 50 uH. Since it takes 2000 uH or more to resonate a > typical LowFER antenna, you'd need to connect quite a few of these coils > in series to make a conventional loading coil. > > For those who feel that the wire in the loading coil is part of the 15 > meter limit, I suppose you could build a conventional pi-network output > circuit into the "transmitter" using one of these coils, and dispense > with the external loading coil completely. K6STI's coil calculation > software predicts a series resistance of about 1.6 ohms for a 108-turn > coil of copper, very slightly less for silver. I'm too lazy and rusty at > the math to do the calculations, but a quick P-Spice simulation yields > the following results: With an antenna equivalent circuit consisting of > a 250 pF capacitor in series with a 20 ohm resistor, and a coil > inductance of 208 uH, the input capacitor on the pi network would need > be about 0.22 uF and the output capacitor about 3600 pF to achieve > resonance in the 180 kHz range, and to provide a 50 ohm load to the > transmitter output circuit. > > For comparison, suppose the inductance is increased to 2900 uH, the > input capacitor is reduced to 0.01 uF and the output capacitor is > reduced to 15 pF. With a coil Q of 200 (about 16 ohms series > resistance), the voltage on the antenna would be about 10 dB higher than > it would using the 208 uH coil. This second circuit is very similar to a > typical LowFER installation where a small variable capacitor is used > across the top of the coil for fine tuning, and a larger capacitor is > used between the bottom of the coil and ground to provide a closer match > to 50 ohms (for those who want their transmitters to see 50 ohms). It is > still actually a pi network, and if you make the transmitter box big > enough, it will fit inside. > > This is a very long way of saying the coils are too small... > > les@highnoonfilm.com wrote: > > > > I've been given the chance to purchase a couple of surplus Nautel antenna > > tuning > > coils salvaged from decommissioned NDB's. They appear to be made of > > silver wire (#10 gauge) wound over fiberglass cores. The coils are 10-14 > > inches > > long and 3 inches in diameter. One of them also has a small ferrite variometer > > in the center that is adjusted using a knob on the side of the cabinet. > > > > -- > Lyle, K0LR > > http://www.computerpro.com/~lyle > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Sun Jul 30 11:51:46 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:37 2003 Subject: [Lf] [Fwd: [Lowfer] NDB Coils] Message-ID: <39844102.B2813187@bellatlantic.net> les@highnoonfilm.com wrote: > I've been given the chance to purchase a couple of surplus Nautel antenna > tuning > coils salvaged from decommissioned NDB's. They appear to be made of > silver wire (#10 gauge) wound over fiberglass cores. The coils are 10-14 > inches > long and 3 inches in diameter. One of them also has a small ferrite variometer > in the center that is adjusted using a knob on the side of the cabinet. > > Has anyone else ever used surplus NDB equipment for lowfer purposes? > I'm not sure how efficient these coils would be compared to our own > homemade coils. > > Les Rayburn, N1LF > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Mon Jul 31 09:02:39 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:37 2003 Subject: [Lf] Spectran beta 4 is released] Message-ID: <39856ADF.B608E48D@bellatlantic.net> Alberto di Bene wrote: > SPECTRAN beta 4, build 110 has been just released. > > Beta 4 is a major enhancement with respect to beta 3. > Full duplex, real time audio processing has been added, > with denoising, bandpassing and CW peaking functions. > > Here are some of the new features : > > - Display of the frequency where the mouse cursor is hovering on. > > - Possibility to switch off the visual AGC (not the audio AGC, but > that AGC that in beta 3 was always applied when computing the > color of the spectrogram). It has been brought to our attention that > with strong QRN this AGC had the side effect of 'chopping' otherwise > quite readable QRSS signals, making difficult to discriminate > between dots and lines. > > - More consistent timing when computing the overlap factor, leading > to a more constant speed of the spectrogram. > > - Semiautomatic procedure for the setting of the Windows mixer. > The Windows mixer is the most non-standard feature of Win9x, > a real nightmare (thanks Bill...). Lacking tight specifications, > every soundcard manufacturer has felt free to implement the mixer > functions in the way they pleased them more. Hopefully the procedure > we have devised to set the mixer should take care of this. > > - Denoiser : the denoiser is of the Widrow-Hoff type, i.e. a FIR filter > whose h coefficients are adjusted in real time with the LMS (Least Mean > Square) algorithm, making the filter to converge towards a dynamic > solution that minimizes the so-called AWGN noise. We have devised a > variant of the standard method, where the leaking factor applied to the > h coefficients has been made proportional to the mean amplitude of the > audio signal. > > - Bandpass : from the low-cut and high-cut limits set with the mouse a > rectangular windows is defined, its IFFT is computed, then a Hamming > window is applied to it, and finally a forward FFT is computed, leading > to a 'well-shaped' filtering window that minimizes the Gibbs phenomenon. > This window is applied to the FFT of the audio signal, which is then > brought again in the time domain with an IFFT, ready for further processing. > You can see a simulation done with Matlab of the final result at this > URL : http://www.weaksignals.com/images/bandpass.gif > The irregularities seen on the stop band are due to the simulation of > rounding the coefficients to 5 significant digits. > > - CW Peaking : this function is simply an IIR resonator, with two zeros > on the real axis at -1 and 1, and two complex conjugate poles at a radius > of 0.995. The angle of the poles is computed in real time, when the frequency > of the desired peak is set with the mouse. This kind of resonator has been > choosen by personal judgement, listening to its effect on CW signals. We > feel that its shape is much more adequate for CW than a 'brick-wall' filter, > even if the stop-band rejection could be better. But you can always use the > CW peak filter and the bandpass filter in cascade, if you so prefer. For those > wanting to see the interesting shape of this filter, there is another > Matlab simulation here : http://www.weaksignals.com/images/cwpeak.gif > A word of warning : the bandpass of this filter is roughly 30 Hz, so if used > with very fast CW it could smooth a bit too much the keying component. > > These more or less are the major enhancements of beta 4. Only a few final words > on how to use them. For the mixer setting, Spectran will recognize the first > execution of beta 4 on a given machine, and will automatically start the setup > procedure. Just follow the simple instructions on the screen, and you will not > be bothered again. > To set the filters, a filter definition panel has been added. If you briefly tap > on either Shift key, the panel will appear. Another tap on the Shift key, and it > will disappear. When it is visible, the left mouse button will set the lower limit > of the bandpass, the right mouse button the upper limit. To set the CW peak frequency, > use the combination Ctrl-Left Mouse Button. > To actually switch the filters on and off the audio processing chain, use the red leds > on the left side of the main Spectran panel. If you want to use them all > simultaneously, you need at least a 166 MHz Pentium if you limit the sampling > frequency to 11025 Hz. For 22050 Hz a 266 MHz Pentium should do. > The 'PassThru' led, when choosen, simply activates the rerouting of the input > signal, unprocessed, to the output. In this mode the signal does not incur in the > delay of about one second between input and output, due to the buffering and > processing. It is intended to make tuning easier (which it isn't with the delay...) > > This should be all. Sorry for the long message, but a bit of explanations were in > order. One last thing : we need your feedback. We 'think' our mixer setting > procedure should take care of all the possible variations around (it did in our > few test cases), but there is always a case you did not anticipate... so please > tell us how it works on your computer with your soundcard. Thanks. > > Spectran beta 4 is freely available here : http:/www.weaksignals.com > > 73 > > Alberto I2PHD > Vittorio IK2CZL From fgentges at mindspring.com Mon Jul 31 18:26:57 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:37 2003 Subject: [Lf] Re: Spectran beta 4 is released References: <39854A05.ACE5CF70@usa.net> Message-ID: <3985EF21.56667152@mindspring.com> When you get a new telescope the sky is cloudy for days on end. When a new version of Spectran comes out, the thunderstorms come rolling in. A quick look is pretty exciting even without more realistic signals. This thing is looking really nice. It found my mixer settings with the new tool. Congratulations to Alberto and Vittorio on this release. Frank Alberto di Bene wrote: > > SPECTRAN beta 4, build 110 has been just released. > > Beta 4 is a major enhancement with respect to beta 3. > Full duplex, real time audio processing has been added, > with denoising, bandpassing and CW peaking functions. > > > Spectran beta 4 is freely available here : http:/www.weaksignals.com > > 73 > > Alberto I2PHD > Vittorio IK2CZL > > _______________________________________________ > Tacos mailing list > Tacos@amrad.org > http://www.amrad.org/mailman/listinfo/tacos -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From akestelo at bellatlantic.net Tue Aug 1 13:03:00 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:37 2003 Subject: [Lf] Really big coils Message-ID: <3986F4B4.7E021770@bellatlantic.net> Cantrell Bill-QA0057 wrote: > Winding a coil from aluminum CATV line, etc. would be similar to using wide > flat strap for the conductor. This is actually less effective than using > Litz wire at LF with the proper strand diameter to # of strands ratio. Its > a fractal-geometry thing involving the skin effect. You get far more usable > surface area with Litz wire in this frequency range than you can get with > flat strap or big dia conductors. (Think of it this way -- there must be > some really good reason to go to all the trouble to manufacture Litz wire -- > it is a pain. If wide strap were just as good or better, Litz wire would > never have existed.) Of course, by the time you get to HF, the > effectiveness of litzendraht is worse compared to flat strap. Hence it is > only used to the MF band. See for instance: > > http://www.wiretron.com/litz.html > > Regards, > Bill > "TEXAS" & WD5CVG From akestelo at bellatlantic.net Tue Aug 1 21:43:15 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:38 2003 Subject: [Lf] [Fwd: [Lowfer] Winding Ferrite loop, Litz size?] Message-ID: <39876EA2.1D9052@bellatlantic.net> Phil Atchley wrote: > Hello all... > Done some NDB's etc, used to use a 4 foot "pancake" wound loop which > now isn't too practical in my new location (where to put it away from > computer etc). Very real estate limited on this mobile home park. So I > haven't done much beacon hunting since moving in here. > > Decided to make a "double" loopstick using 2 15" ferrite bars to cover > the Longwave band and the BCB band, put these one above the other on a > common rotator which I want to mount on top of the pushup tv mast supporting > my sloper (about 25 feet above the metal roof). This is about as far as I > can get an antenna from the "stuff" in the home and neighbors homes, my only > concern is that the sloper may "re-radiate" into the loops but that can't be > helped. > > My intent is to remotely switch the two loops into the front end of a > fet balanced amplifier which will be varacter tuned and mounted between the > two loops, output of the amplifier fed to the "shack" via coax. > > My questions are these. (many of them) > > 1. I presume I want to wind the VLF loopstick with litz wire. (already have > a coil on the BCB loopstick) I see where Amidon has Litz in 8/42, 8/44 and > 10/44 sizes. Since the cost is the same does anybody know which would be > better for the coil? I haven't yet determined the number of turns needed. > > 2. The two loopsticks will be in the same plane but since the two > loopsticks (two 7.5 inch rods superglued end to end) will be tuning > different frequency ranges I don't expect a lot of interaction between them > between them but does anybody have a feel about a reasonable spacing between > them with the amplifier between? > > 3. I've read about putting the loopsticks in an aluminium "trough" (sp?) to > act as an electrostatic shield. Anybody tried this, detuning effects, loss > of "Q" and loss of gain??? How did you make the "trough"? > > This will be using PVC pipe construction to insure the entire thing is > weathertight, of a sufficiently large cross section to fit the rotator > (which I still need to get). > > 73 de Phil KO6BB > If it's more than 1dB above the Noise Floor "IT AIN"T DX"! > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Tue Aug 1 21:51:18 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:38 2003 Subject: [Lf] [Fwd: [Lowfer] Really big coils- VA3LK] Message-ID: <39877086.FB5AD3E8@bellatlantic.net> Larry Kayser wrote: > Paul es group..... > > >I wonder if anyone has tried building a really big coil out of CATV line. > >I can easily be formed into 3 or 4 foot dia circles and even more. With the > >right lenght to > >dia. ratio yield a very hi Q coil. The cable diameter .5" to 1.125" and is > >relatively light. > > > >Might be OK for base loading. Any ideas on this crazy scheme. > > I have tried using some black jacket aluminum shield coax here at the 4 ft > diameter and I was not able to in the few hours I had to work on it make the > coil perform. I unrolled the coax and used it as a radial were it made a > measureable contribution. IF I have the sense right very high performance > coils, Hi Q included are when the coil approaches square, diameter by > length. The Q seems to improve quickly when one goes to an odd number of > vertical winding posts and creates what I think is called the basket weave. > My next series of loading coils here will be LITZ wire on a basket weave in > a square format with a small variometer at the top for screwdriver motor > tuning under PC control. > > >Also has anyone heard VA3LK on 137.710. I am very dissapointed that I > >cannot hear/see him using > >Spectran 4.0 and a 200 foot long wire. I heard that there was a good > signal > >in Western PA and also that someone > >1100 miles away recently copied him I gotta be doing something wrong. > >137.710 correct with 800 Hz CW note? > >Also no sign of his friend 14 Hz down. > > There are a number of issues for this, not sure of all of them but a 200 ft > long wire is from my experience here a lousy LF receiving antenna. My best > results last winter were with a 1000, 2000, and 4000 ft Beverages laying on > the ground, terminated in about 500 ohms and using copper pipes bashed into > the ground - which is really horizontal under the soil and above the rock > hi. I have an email from a chap in Maine who copies the test signal on his > speaker most of the time, his antenna is very significant, ie big. From my > meager experience it is essential to go through a very hard learning curve > with this LF receiving bit, hearing weak signals is a complete layer of > significant effort under the general listening on LF. > > I offer this hint. I have a large coil and capacitor that is series > connected on any broadband antenna to resonate on 137 kHz. This assembly > makes and amazing difference for weak signal reception. > > The last point was that I have learned that the use of the DSP programs Gram > etc. need to be diddled a lot to get the last few dB out of them. When I > was looking for WA2XTF (AMRAD beacons in the Washington area) I spent months > seeing a faint line that I came to know was them, the second signal 5 Hz > away was similarly there but not readable (and it never has been readable > here). One after noon I looked up and there on the screen was the complete > call sign. The point of this comment is that I was near the threshold for a > long time before I managed to pull them out of the mud. My total of heard > reports for the test transmissions from here on 137.710 is now over 20, I > know this as I am making up the SWL/QSL cards for those who have been kind > enough to send in reports. I know that if you are not able to hear the NPG > rtty on 135.95 at times that you will not hear me. If you need the full > data on NPG let me know I will get my log book and send you a summary of > information on that signal. > > The VA3LK test signal on 137.710 continues at this time transmitting EVEN > hours UTC with .4 wpm CW. If you are having trouble identifying the signal > I can send you a .jpg of what others are seeing so you can have a sense of > finding the signal in the noise. > > 73 > > Larry > VA3LK > > _______________________________________________ > Tacos mailing list > Tacos@amrad.org > http://www.amrad.org/mailman/listinfo/tacos From riese-k3djc at juno.com Wed Aug 2 21:40:37 2000 From: riese-k3djc at juno.com (Bob RIESE) Date: Thu Jul 3 13:42:38 2003 Subject: [Lf] look for the silver lining Message-ID: <20000802.204039.-191431.2.riese-k3djc@juno.com> Any idea when the bk will be back on the air I was interested in doing some receiver compares but NO BEACON kinda like that telescope Frank HI Bob From akestelo at bellatlantic.net Tue Aug 1 13:14:33 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:38 2003 Subject: [Lf] Re: Spectran beta 4 References: <3986DDDB.511B4CE0@usa.net> Message-ID: <3986F769.ABA78417@bellatlantic.net> Hello Alberto, I have not encountred any problem when installing Spectran 4 onto my Toshiba 1555 CDS laptop. (FYI : 380 MHz AMD K6-2; ESS ES1978S (PCI audio accelerator) supporting 18-bit stereo, Windows Sound System and Sound Blaster Pro-compatible 3D sound support) Thanks for all your efforts 73 Andre' Kesteloot N4ICK ********************************************************* Alberto di Bene wrote: > Hi all, > this message is sent to all the reflectors where originally I sent > the announcement of the beta 4 version of Spectran. From halfei at erols.com Thu Aug 3 22:39:48 2000 From: halfei at erols.com (Hal) Date: Thu Jul 3 13:42:38 2003 Subject: [Lf] look for the silver lining In-Reply-To: <20000802.204039.-191431.2.riese-k3djc@juno.com> Message-ID: <4.3.2.7.2.20000803213836.00aef440@pop.erols.com> At 08:40 PM 8/2/00 -0400, Bob RIESE wrote: Took the beacon down because of all the lightning we have been having. I will bring it back up tonight (Thursday). H >Any idea when the bk will be back on the air >I was interested in doing some receiver compares >but NO BEACON > >kinda like that telescope Frank HI > >Bob > >_______________________________________________ >lf mailing list >lf@amrad.org >http://www.amrad.org/mailman/listinfo/lf From akestelo at bellatlantic.net Fri Aug 4 09:29:43 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:39 2003 Subject: [Lf] Re:Message from N1LF Message-ID: <398AB737.54BDEA37@bellatlantic.net> Tod - ID wrote: > N1LF wrote: > > > Last week I called ARRL headquarters to ask about the ARRL's > > LF Petition status. I was told that we could still file comments > > and ask about the status of the petition. Headquarters promised > > to get back to me with information about how to do that > > electronically. Two weeks, not a beep. > > > > I plan to call again tomorrow and start over. Same thing with the > > LWCA, if we can become only a little more organized, then > > we could file petitions ourselves and develop some official > > standing with the FCC, ARRL, etc. > > > > Lowfers are 'recognized' by ARRL. There has been at least one article in QST > in the last several years. Mark Wilson, the person at ARRL responsible for > ARRL publications (including QST) has asked me to help him find people who > will write articles that can be published to help people start operation on > a 160 kHz band once it is allocated by the FCC. (I have discussed it with a > couple of people on this reflector). A petition for rule making (RM-9404) > was filed October 22, 1998 and is still pending (which is why you can > comment on it). > > During the July, 2000 meeting of the ARRL Board the General Counsel of the > League, Chris Imlay, W3KD, reported on the status of Frequency allocation > issues now active. The 160kHz petition was number 5 on the list of 12 > items, Very immediate threats to the 2.3 GHz and 2.4 GHz bands were items > #1, #3 and #4; Part 15 emissions were covered in item #2. > > Because all written and oral communications from the General Counsel during > a Board meeting are covered by lawyer-client privilege I am not able to > repeat in detail Mr. Imlay's words. He did state that he has checked > regularly on the progress of the RM-9404 and in his most recent > conversation he was told that processing the request had been delayed by > "more urgent deadlines". > > I am under the impression that he has been informed that a draft document > has been created by OET (Office of Experimental Technology), but has not > been released to the entire Commission. Apparently the OET is concerned > about interference to utilities. It is my further impression that there will > be a meeting in Washington in September between FCC and ARRL representatives > and this petition is on the agenda. Prior to that meeting I would expect > Imlay to meet with FCC staff to sort through concerns so that the September > meeting will be 'smooth'. Such an earlier meeting would involve Imlay, Dick > Wilder, a technical consultant who created the initial request for ARRL, and > perhaps some of the AMRAD people. > > I suggest that the few hundred LOWFERs currently active in the US probably > can not bring much additional political pressure to bear on this matter (at > least in the eyes of the FCC). However, it cannot hurt to write to the OET > and share with them your thoughts on just how much interference the power > companies are likely to experience. Especially since there have been no > reported cases of interference from GWEN. (The utilities are not protected > from interference on these frequencies by current rules anyway). Other > comments that may be constructive would be good too. > > It is my opinion that if there is going to be an FCC allocation to amateurs > on the LOWFER frequencies it will come from RM-9404. As far as operating > according to the "rules" that apply to the LOWFER frequencies I suggest that > the LOWFERS are doing the correct thing by settling upon a 'reasonable' > interpretation of the written text and then proceeding to operate. It is > inconceivable to me that there will be a large scale FCC investigation and > "bust" aimed at capturing scofflaw LOWFERs. > > Tod, K?TO From akestelo at bellatlantic.net Fri Aug 4 14:50:43 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:39 2003 Subject: [Lf] VLF, Interference, the Utilities] Message-ID: <398B0273.88E4BB4@bellatlantic.net> Steve Dove wrote: > Greetings, > > It's always struck me that the utilities' arm-waving as to their > susceptibility to interference is disingenuous. Their real concern is > something else. > > Right now, in the Part 15 environment, they have next to no liability > for interference _caused by themselves_ at all. Which would change if > a licensed service such as is proposed came into being; they'd then > have to dance the non-interference dance which would be a major pain to > them, satisfying near endless whinges and complaints; they may even > foresee their PLC systems dying a death of a thousand cuts as a > consequence. > > 73 > > Steve W3EEE > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Fri Aug 4 14:50:03 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:39 2003 Subject: [Lf] PowerLine carriers Message-ID: <398B024B.BB73DAED@bellatlantic.net> Lyle Koehler wrote: > Power line carrier systems operate under Part 15 rather than as a > licensed service. They are subject to the same rules and have the same > "rights" (essentially, none) as other Part 15 users, at least as I read > Section 15.5 (reproduced below) > > Section 15.5 General conditions of operation. > (a) Persons operating intentional or unintentional radiators shall not > be deemed to have any > vested or recognizable right to continued use of any given frequency by > virtue of prior registration or > certification of equipment, or, for power line carrier systems, on the > basis of prior notification of use > pursuant to Section 90.63(g) of this chapter. > (b) Operation of an intentional, unintentional, or incidental radiator > is subject to the conditions > that no harmful interference is caused and that interference must be > accepted that may be caused by > the operation of an authorized radio station, by another intentional or > unintentional radiator, by > industrial, scientific and medical (ISM) equipment, or by an incidental > radiator. > (c) The operator of a radio frequency device shall be required to cease > operating the device > upon notification by a Commission representative that the device is > causing harmful interference. > Operation shall not resume until the condition causing the harmful > interference has been corrected. > (d) Intentional radiators that produce Class B emissions (damped wave) > are prohibited. > > -- > Lyle, K0LR > > http://www.computerpro.com/~lyle > > Peter Barick wrote: > > > > Re: VLF Interference And The Utilities > > > > K0TO's deliberate comments on lowfers operations and proposed low-band > > amateur licensing are well taken. However his contention that the > > utilities "are not protected from interference" in the low-band raised > > some concerns by this reader. It would seem that they along with major > > broadcasting services would *all* be covered by interference regulations > > of the FCC to achieve their public service commitments. > > > > Could someone comment on this point? > > > > Peter Barick, Sycamore Il > > > > >>> "Tod - ID" 08/03/00 10:26PM >>> > > N1LF wrote: > > > > > Last week I called ARRL headquarters to ask about the ARRL's > > > LF Petition status. > > <> > > > > <> > > > > Especially since there have been no > > reported cases of interference from GWEN. (The utilities are not > > protected > > from interference on these frequencies by current rules anyway). Other > > comments that may be constructive would be good too. > > <> > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > > send to list!!) Send on list submissions to lowfer@qth.net > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Fri Aug 4 13:56:00 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:39 2003 Subject: [Lf] ARRL Petition for Rulemaking (RM-9404)] Message-ID: <398AF59F.9AD3A9C4@bellatlantic.net> les@highnoonfilm.com wrote: > Thanks to Tod, K?TO for providing all of us with an update on this > proceeding. As all of > us should be aware, representatives of the electric power industry opposed > this > petition (or at least the portion of it that relates to 160-190khz) > otherwise, it > is very likely that we would already have an amateur LF allocation. > > Their concern is that widespread amateur operation would cause interference to > PLC operation, which has Tod and the ARRL have pointed out is not protected > from interference anyway. Further, since GWEN operated at various sites > around the country for years, with ERP's that no amateur could hope to match, > there is real evidence to site that disputes their concerns. > > Tod, what would be the best way for those of us who wish to offer > additional comments > to proceed? I have found two web site's that would seem to make this easy > to do: > > FCC's Electronic Comment Filing System (ECFS) > http://www.fcc.gov/e-file/ecfs.html > > FCC Office of Engineering and Technology > http://www.fcc.gov/oet/ > > I think it would be appropriate to point out the advancement to the radio > arts that have > already been made by Part 15 experimenters in this range (many of them hams) > and also I think the commission should be made aware that there is unlikely to > ever be widespread commercial equipment available for this band (the LF > allocations in other countries have not sent Kenwood rushing to make > new LF rigs) so amateur density in this band is likely to be small. More like > microwaves than HF. > > I will yield to Tod's suggestions, and I think we should wait until he advises > us on how to best proceed. But then, I think we all should comment, at least > so that the LWCA has a voice, and so that the commission knows that > amateurs really do want this spectrum. > > Les Rayburn, N1LF > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Fri Aug 4 13:50:50 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:40 2003 Subject: [Lf] RE:Aerial info etc.] Message-ID: <398AF46A.5503E044@bellatlantic.net> Talbot Andrew wrote: > The equation for capacitance of a wire above a groundplane, as given in > any textbook of electromagnetism, includes a term LOG(diameter) so > there will be diminishing returns on wider spacing . Capacitance is > proportional to length, so it looks as if for a given amount of copper, > length will win over multiple parallel wires any time. OK for those > with decent sized gardens......... > As for the actual ground loss, I rather like Laurie's shower head > analogy, it sort of makes intuitive sense. > > Still does not answer why my tiny antenna system has ONLY 100 ohms loss > resistance, compared with some other much bigger systems described here > with higher values than this. > > Andy G4JNT > > > ---------- > > From: LAWRENCE MAYHEAD[SMTP:LAURIE@g3aqc.freeserve.co.uk] > > Reply To: rsgb_lf_group@blacksheep.org > > Sent: 2000-08-04 08:41 > > To: rsgb lf group > > Subject: LF: Re. Aerial info etc. > > > > Hi Alan, > > "Whoops" looks like I have mis-lead you! > > The 700uH does not resonate the Ant.,I need another 1mh at the base to > > do that. > > When the top inductor is not in use the base inductance is about > > 1.6mh.This gives a total capacity of 855pf. Rik Strobbe gives some > > useful figures for the cap. of vert and horiz wires,about 6pf/m at 15m > > height,so allowing about 100pf for the vert part this leaves 755pf. > > So.755/6=125m. This probably about right since my top wires are close > > together at times and not all the 160m are effective.I have used Eznec > > to model my Ant.and it shows that the current in the vert. section is > > almost constant(drops from 1A down to 0.97A at the top) so the > > effective height of the Ant. is almost equal to the actual height.So > > there is not much more to be gained in this area which is why the top > > inductor was ineffective,with less cap. loading I am sure it would > > have been useful. > > I still wonder wether there scope for a further reduction in loss > > resistance by putting in more top wire ?or is there a law of > > diminishing return here also.I would also like to investigate wether > > its better to have one long topwire(doesnt matter if its bent) or > > wether several wires in parallel.would be as effective.But this must > > wait,unless someone else can do the experiment! > > Finally I agree about the 10ft radial but I am sure there is more to > > it than this,we come back to ground penetration,"shower heads" etc > > .73s Laurie. > > > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution, > or any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From halfei at erols.com Sun Aug 6 23:32:30 2000 From: halfei at erols.com (hal) Date: Thu Jul 3 13:42:40 2003 Subject: [Lf] look for the silver lining References: <4.3.2.7.2.20000803213836.00aef440@pop.erols.com> Message-ID: <398E1FBE.CA0C1196@erols.com> I took the liberty of changing the beacon format hopefully to make it more useful. VVV de callsign, 3 seconds silence followed by three 15 second dashes with a one second gap between dashs and then a brief off period before repeating. H ----------- Hal wrote: > At 08:40 PM 8/2/00 -0400, Bob RIESE wrote: > > Took the beacon down because of all the lightning we have been having. > I will bring it back up tonight (Thursday). H > > >Any idea when the bk will be back on the air > >I was interested in doing some receiver compares > >but NO BEACON > > > >kinda like that telescope Frank HI > > > >Bob > > > >_______________________________________________ > >lf mailing list > >lf@amrad.org > >http://www.amrad.org/mailman/listinfo/lf > > _______________________________________________ > lf mailing list > lf@amrad.org > http://www.amrad.org/mailman/listinfo/lf From fgentges at mindspring.com Wed Aug 9 00:53:07 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:40 2003 Subject: [Lf] AMRAD Meeting Message-ID: <3990D5A3.F6DF7423@mindspring.com> Hi, I have a basic LF skywave program that Doug Hensen has written. I have done a simple data run based on the Paris France to Nags Head path for January 15th. I will have the program and the data this Thursday for all to examine and discuss. Frank -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From akestelo at bellatlantic.net Fri Aug 11 18:55:28 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:40 2003 Subject: [Lf] Insulated Support Towers] Message-ID: <39947650.36CF305B@bellatlantic.net> les@highnoonfilm.com wrote: > My beacon uses a "T" type antenna, supported on both ends by masts. I have > attempted > to insulate both of these masts from ground, but am concerned that the > taller 45 foot > mast by have some leakage paths to ground (it is secured to a grounded > chain link > fence, insulated only by a wooden board) > > For the purposes of the argument, let's assume that the support tower is > grounded, but > that the flattop is itself is well insulated. (it is with two dogbone > insulators and nylon rope) > > What would the likely effect be for having a grounded support tower on one > in of the > flattop? The support tower would be at least 50 feet from the vertical > section and > a good 15 feet from the tophat section. > > (I'm trying to decide if it's worth the considerable trouble to really > insulate this mast) > > Les Rayburn, N1LF > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Sat Aug 12 10:54:36 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:41 2003 Subject: [Lf] re LF aerials] Message-ID: <3995571C.B8EFCDCA@bellatlantic.net> les@highnoonfilm.com wrote: > I did an article in the Lowdown (publication of the LWCA) on this subject > about ten years ago. I was fortunate at the time to be working as a > communications officer onboard a nuclear submarine that was > undergoing overhaul in Kittery, Maine. > > At the time, I was operating a one watt lowfer beacon on 184khz > about 14 miles away. Since I had access to lots of LF test > equipment onboard (calibrated F/S meters, antenna current > meters, etc.) I decided to test a number of ground systems. > > The basic rules of thumb appear to be the same for LF > as they are elsewhere with short verticals. On LF > it is easy to get misleading readings, esp. if you're metering > in the near field. (We lowfers found this out the hard way) > > To lower ground losses, the best bets are: > > 1. Get as much metal as possible at the base of the antenna. > Meaning if you only have 400m of copper wire, you're better > off putting down 32 short radials than one or two long ones. > > 2. "The Law of Diminishing Returns". We've also found > out through hard experience a simple rule. In order to > see an increase in antenna current, you have to double > the number of radials. For instance, put down 2 radials > vs a ground rod...you'll see an improvement. To see any > more improvement, you have to put down 4, then 8, > 16, then 32, then.... > > Soil conditions do make a difference. But not as great as > some of the effects you seem to be observing. > > I think that the amateur allocation in Europe is a significant > change in LF in one area. Most of the installations are > of the "backyard" variety, where as here in the states, > LF activity is mainly limited to those who have > some real estate to work with. > > You must consider the fact that any nearby objects, > (trees, homes, gardens, etc.) have a VERY significant > effect on the total system losses. You can easily couple > 90% of your signal into these objects. These objects > will also affect any and all measurements that you make > in the near field. > > Putting up bigger tophats, may also mean that those wires > are brought closer to nearby objects, thus changing the > system losses. > > In short, there are no "rules" and John is very right > to caution against making blanket statements. It > flies in the face of logic and experience to suggest > that a single ground rod would outperform a large > radial system. I would suggest looking hard for > other ex plantations to your situation (such as > coupling to nearby objects) > > Backyard systems are rarely going to approach > the performance of commercial antennas mounted > in the clear with good radials. So, another factor > is to be realistic about what you can expect from > your own situation. > > Les Rayburn, N1LF > XMGR (186.404khz) From akestelo at bellatlantic.net Sat Aug 12 16:37:38 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:41 2003 Subject: [Lf] Lowfer Transmitter] Message-ID: <3995A781.F3603DBF@bellatlantic.net> Frederick Davidson wrote: > http://www.home.earthlink.net/~fredsworld/ > This is a Web Page I have started to post projects: R.F., A.F. and Misc. > I have put on the first page some of the work I have been doing on a lowfer > transmitter. > I have shown parts layout and the film for making a pc board. > The parts list is coming soon. > The parts cost around $25.00 and that includes the material for the pc board > but not for making it. > > Red > K0RAJ > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Sat Aug 12 16:51:34 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:41 2003 Subject: [Lf] Utility PLC Interference] Message-ID: <3995AAC5.281D6A0A@bellatlantic.net> Richard Brunner wrote: > " K0TO's deliberate comments on lowfers operations and proposed low-band > amateur licensing are well taken. However his contention that the > utilities "are not protected from interference" in the low-band raised > some concerns by this reader" > > The last time that amateur operation was proposed for 160-190 kc, there was > a very emotional response from the utility people, fearing disasters. It > was a case of the blind leading the blind, or people in charge knowing > nothing about it, but fearing the worst. Hopefully this time discussion > will be rational. In theory, unlicensed operation, (PLC's) has no standing > and cannot complain about interference. > > Utility PLC's are inherently self-protected against interference-caused > maloperation. Unless my memory has failed, when they operate something, > they shift frequency about 500 cycles, and increase output 10 dB to assure > working through a faulted line. What we hear, (that dead carrier) is merely > a keep-alive indicator showing that it is active. QRM will have no effect > because at least two things must happen to have any effect; the keep-alive > carrier disappear and the new one appear. > > Note also that power lines are a very rf-noisy environment, which anyone who > has driven under power lines can attest. Thus, PLC receiver sensitivity > ranges from millivolts to volts. They will never hear a transmitted signal, > and indeed, the only places they have had trouble was in the vicinity of > high-power military transmitters. At best, under ideal conditions, they may > weakly hear Loran-C. > > I will write this up, in detail, with documentation, and submit to the FCC. > > Richard Brunner, AA1P, rbrunner@gis.net > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Sat Aug 12 17:01:30 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:41 2003 Subject: [Lf] Experimental LF transmitter] Message-ID: <3995AD1A.A50171EE@bellatlantic.net> Richard Rogers wrote: > G'day All, > > I now have my PIC running at 10.245MHz, generating 182.9KHz, with 43% duty > cycle. > > I measured the TX output as 196 watts at 104% efficiency with 5 volts on > the driver and 205W and 114% with 12V! > > These odd figures turned out to be because my dummy load was not 50ohms, > but 58ohms. The corrected figures are 169W at 90% and 176W at 96%. I > suspect these are probably not accurate also, but at least the trend is > clear. There is now a slight improvement with the higher drive voltage. > > The loss formulae in the Hitachi book are a bit hard to explain without > their diagram so I'll simplify it a bit by neglecting the switch on loss. > > I assume they mean f to be frequency. t2 = on time and Ip is the peak of > the triangular drain current, then P2 = (f x t2 x Rds x Ip^2)/3. > > For the switch off loss, t3 is the switching time and Vp is the peak drain > voltage, then P3 = (f x t3 (Vp x Ip + 2 x Ip^2 x Rds))/6 > > I'll check these with f=180K, t2=5.4uS, Rds=.1, Ip=20, t3=200nS, Vp=80 > Then P2 = 13W and P3 = 10W > > Many thanks for your help. > > 73, Ric, VK7RO From akestelo at bellatlantic.net Sat Aug 12 17:05:30 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:41 2003 Subject: [Lf] LF Aerials] Message-ID: <3995AE0A.35974722@bellatlantic.net> James Moritz wrote: > Dear LF Group, > > All the professional texts say that ground losses are the most > significant factor that lead to reduced efficiency of antennas at LF > and VLF, and grounding improvements have been the most > effective way of increasing the efficiency of these antennas. But > except for a lucky few, amateur antennas start off with increased > sources of loss that are not possible to eliminate, such as the > proximity to buildings and trees. Also, the height of amateur > antennas is restricted for various reasons. > > Most amateur antennas are less than 20m high; this puts the scale > of them more on a par with professional VLF antennas than LF > antennas - for example a 100m high antenna at 17.2kHz has the > same radiation resistance as a 12.6m high antenna at 136kHz. But > I doubt if any such VLF antennas are supported by 150m trees, or > surrounded by 100m high buildings! For these reasons it is not > suprising that amateur LF antennas behave in a different way to > commercial LF and VLF antennas, and so different rules can be > expected to apply. > > It's worth getting things into perspective - for example: > > The Puckeridge Decca station had a 99m high mast, with 36 buried > ground radials about 120m long (quite modest for a commercial LF > antenna). This had a total loss resistance of about 3 ohms at > 136kHz (not including the loading coil), plus about 0.6 ohms > radiation resistance. Nominal capacitance was 3750pF. > > The SAQ antenna has an antenna current of 600A with 200kW > input, implying a total loss resistance (including the loading coils) of > about 0.5ohms, whilst with an effective height of roughly 100m, it's > radiation resistance should be about 0.05ohms at 17.2kHz. Other > VLF antennas have even lower loss, some less than 0.1ohm. > Typically, capacitances are in the range 10's of nanofarads. > > The 'small' antenna that we put up at Puckeridge (in an open field) > was typical of a modest amateur LF antenna. This was a 42m long, > 9m high inverted L with a single top wire. The earth system was 4 > ground rods in a 2m radius around the antenna downlead. Loss > resistance (not including the loading coil) was about 25ohms, > radiation resistance about 0.02 ohms. Capacitance was about > 280pF. When moved to my home QTH, using an identical ground > system, capacitance was unchanged, but the loss resistance > increased to 40ohms. > > As far as grounds go, my experience has been similar to others. > increasing the extent of my ground system reduced the loss > resistance of my main antenna from about 80ohms to about > 50ohms, but further increases have had minimal effect. It is > interesting to note that the 42m inverted L had a slightly lower > resistance than the main antenna, in spite of having a much > smaller ground system. This suggests that other factors are now > dominant in the case of the main antenna. Indeed, the 42m wire > was further from the trees and buildings, which might account for > the difference. > > It is also worth noting that amateur LF antennas are much higher > impedance devices than their commercial counterparts - their > impedance is mostly a few kilohms of capacitive reactance, of the > order of 10 times higher than the commercial antennas - which > combined with lower heights means the voltage gradient they > produce will be much greater for a given antenna current. With 10 > times the voltage on the top section of the antenna, and one tenth > of the height, the electric field strength produced for the same input > current would be 100 times as great. This suggests that dielectric > losses would be much more significant in the case of amateur > antennas than the professional ones. > > The grounds used by professional antennas are usually in the form > of a continuous mat extending quite a way beyond the antenna. > This means that almost all the electric field produced by the > antenna will be screened by the ground mat, and so will not > penetrate into the ground far. Most amateurs cannot reproduce > this, and have a much more sparse system of ground radials and > rods. This would enable the field produced by the antenna to > penetrate much further into the ground; the text books say that the > 'skin depth' at LF should be many metres. This could have 2 effects > - one the one hand, desireable in that the height of the antenna > may effectively be increased. On the other hand, undesireably, > earth has rather high dielectric losses, so would be expected to > increase the loss resistance of the antenna. Since amateur > antennas are lower height, a greater proportion of the field will be > in the ground, and therefore subject to losses of this type, so again > these effects would be more significant with amateur antennas. > > The difficulty of trying to prove any of this, or trying to put numbers > to the different losses, is in trying to isolate different effects. Short > of running amok with a chain saw, it isn't practical to eliminate the > losses due to trees and buildings. Changing the capacitance of the > antenna means the loading coil must be altered, and the change of > losses in the coil must be taken into account. Moving the antenna > will change the distribution of ground currents, and so the ground > resistance. It isn't easy to find an open field where people don't > mind you burying miles of wire and so on. Likewise, since > everybody's QTH is different, what works for one station may be > no good for another. The best thing we can all do is to try as many > experiments as possible, and hope that useful conclusions can be > drawn from the collected results. > > Cheers, Jim Moritz > 73 de M0BMU From akestelo at bellatlantic.net Sat Aug 12 17:24:36 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:42 2003 Subject: [Lf] re LF aerials] Message-ID: <3995B284.E86AA6F6@bellatlantic.net> Alan Melia wrote: > Hi John, your comments all noted. I see the reason why this is so > interesting is that it 'seems' to contradict the generally agreed wisdom. > > I have a few thoughts on this.... > > Could it be that it is a matter of size? > As a comparison laying a 100m counterpoise or gound wire on 136kHz would be > the equivalent on 80m to putting down a 10foot 'radial'. I think the general > opinion is that that would not be very significant. Most professionals are > dealing with bigger verticals and very few would need to go in for top-loads > of the order of 160m (may be wrong there I have no experience in this area) > > Is it one of money? > I suspect the standard NDB T aerial is an economic choice as well as a > technical compromise. The radiation resistance does not seem to increase > much after the arms are about equal to the height, so you stop there and > bury lots of radials, which is much cheaper than more masts and lots of wire > in the sky. Many seem to use umbrella format which is less than optimum > technically but only requires one expensive mast. > > I am not trying to be awkward but I have worked in 'research' and know that > cash constraints means you try what is most likely to work, not pursue all > the variables in a pure and ideal scientific way. > > You are right that in some cases it is 'cost effective' to put down more > earths, but the picture we are beginning to see is that this is for the case > with stations on very good conductivity grounds (like Dick PA0SE, and > probably Graham G3XTZ) Laurie already has a fairly extensive earthing system > for his HF aerials. So he has a fair amount of copper in the ground. I > believe with his soil resistance he may have reached the diminishing returns > point....unless he starts putting out 136kHz quarter waves! > > Do these points hold any merit in your opinion? I think we could be finding > some guides to improving the radiated signal for stations living over poor > ground conditions, if only we can quantify what we are seeing. It could also > have major influence on the cave radio people, who are often operating over > granite outcrops with very little in the way of conductive soil around. > > I think we can also see the beginnings of an explanation why there is so > much difference in different sites. It might be interesting to see some > similar measuremnts to Laurie's from Oz where the ground must be quite bad. > > Whoops I'm getting into bore mode again! but I think this topic is going to > run....and run. > Cheers de Alan G3NYK > Alan.Melia@btinternet.com From akestelo at bellatlantic.net Sat Aug 12 17:26:28 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:42 2003 Subject: [Lf] Insulated Support Towers] Message-ID: <3995B2F4.52CD05B0@bellatlantic.net> Lyle Koehler wrote: > I've done some very limited computer modeling efforts in which "trees" > were simulated by grounded vertical wires with resistive loads inserted > in the middle. If the resistance is very high, corresponding to an > isolated mast, or very low, which would be the case for a grounded metal > mast, there isn't much effect even if the "tree" is within 30 feet of > the antenna. For this crude type of model, losses were most significant > when the resistor in the middle of the "tree" was a few thousand ohms. > My first choice from an electrical standpoint would be to insulate the > mast with a piece of heavy PVC pipe. If that isn't mechanically > acceptable, then ground it. Probably the present arrangement with the > board insulator is just fine, unless the board is wet and the path > between mast and chain link fence is short. > > One of the support towers for my LEK antenna is within 15 feet of the > flat top. A 3-foot piece of 4" diameter schedule 40 PVC pipe is used as > a base insulator for the tower, and it's guyed with 3/16" black Dacron > "antenna rope". Hasn't arced over yet :-) > -- > Lyle, K0LR > > http://www.computerpro.com/~lyle > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Sat Aug 12 17:25:39 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:42 2003 Subject: [Lf] LF: Aerials and grounds ..Les N1LF] Message-ID: <3995B2C3.F430F777@bellatlantic.net> Alan Melia wrote: > Hi Les thanks for your input, all experimental data is of immense interest. > > The subtle difference is that I suspect we are not talking about quite the > same type of antenna. As I understand it 'Lowfer' beacons are restricted to > 50feet total from the terminal of the TX. This means most of the antenna has > to be vertical, with a small amount in capacity hat top-loading. I believe > these aerials do perform as you say. > > We seem to have a slightly different effect when we are considering an > inverted L configuration, which differs depending upon the ground > conductivity of the site. It would seem from some experimental data as > though the configuration of the top-load wires can significantly reduce the > ground loss, without apparently increasing the top-load capacity. In these > aerials the height of the vertical is about 10 to 15m (33 to 50ft) and the > horizontal top-load wires totalling 90 to 150m. Mike raises the point of the > 'phasing' of various grounded components, but I think we may be stumbling on > a simpler explanation. This seems to be related to the 'footprint' of the > top-load wire. I am trying to beat the data into some sense at the moment > but not succeeding as I either don't have enough, or its not detailed > enough. (I am not sure which). > > The 'punch line' from the idea seems to be that whilst it is not worth > spreading multiple top-load wires further apart than about 0.8m because you > dont get any further increase in capacity, a wide separation might lead to > lower measured ground loss (BUT ONLY ON SITES WITH A LOW GROUND > CONDUCTIVITY, where putting extra copper in does not make any improvement) > It also might go some way towards explaining why very long low resonated > antennas work so well, when the 'theory' says they should not. > > It may all be rubbish, but its an interesting pass-time for the static > season!! > > Cheers de Alan G3NYK > Alan.Melia@btinternet.com From akestelo at bellatlantic.net Sun Aug 13 07:54:58 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:42 2003 Subject: [Lf] [Fwd: LF: Solar effects on the N.Atlantic path] Message-ID: <39967E82.CEFD4F59@bellatlantic.net> Alan Melia wrote: > Hi All, as I suggested yesterday there has been some unusual results again > today. CFH, Halifax, NS has been just visible virtually all day. It may be a > triumph of optimism over reality, but, after disappearing at its usual > post-dawn time around 0600z, from 0954z this morning there has been a weak > dribble of pixels down the screen at exactly 85Hz spacing very stable > straddling 137.00kHz, but not even forming a continous line, right through > to 2000z dusk at this location. There has been a series of C class X-ray > events culminating in an M1.1 event timed at 0945z and followed by levels > around C2.5. In my experience C class events do not normally lead to daytime > enhancement of CFH so the effect must be related to the other effects due to > the arrival of the coronal mass ejection 'bubble' yesterday. > > We are gathering evidence of an interesting effect. John VE1ZJ is seeing > DCF28 and 39 nearly every afternoon between 1200 and 1400z sometimes later. > This has not correlated with the appearance of CFH which is still exactly > correlated with X-ray events about M1.0. I have not checked the powers but > I suspect that DCF28 and 39 are radiating more ERP than CFH. At the moment > there is no specfic solar event we can tie this to, though the sun has a > fair amount of 'indigestion' at the moment! Maybe it should take its > hydrogen with a little more water !! > > Perseids wasn't very exciting here optically....I saw two trails at about > 2300z, but there was a small amount of high thin coastal cloud and a fair > bit of light pollution. > > Cheers de Alan G3NYK > Alan.Melia@btinternet.com From akestelo at bellatlantic.net Sun Aug 13 16:02:07 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:43 2003 Subject: [Lf] re Basket weave] Message-ID: <3996F0AE.30122BB@bellatlantic.net> cesare tagliabue wrote: > Hello Alan, John & others > Yes, Alan, the given Wheeler formula is valid however for a single spiral, > unfortunately I've never found specific tools for calculate a multi-pie > coil. An alternate > way to roughly evaluate the inductance of such a coil is to regard it as a > normal > multi-layer coil with turns regularly distributed in its cross section and > use another > formula by Wheeler: L = 0.8 a^2 N^2 / ( 6a + 9l + 10c ), where a= mean > radius of > winding, l=length of coil and c=radial dimension of pies, obviously in > inches. > If the radial dimension of pies is small compared with its mean radius and > the coil is made with a large number of pies, so its length is considerable, > there is > another approximate formula: L = a^2 N^2 / ( 9a + 10l) - c a N^2 / (10 pi > l), where > a,l,c are the same as in the previous one and pi = 3.14. I don't know what > is more > accurate but I believe both are enough good for solving our problems. If the > radial > dimension of pies is small, that is no many turns each, the space between > pies > may be also small being the voltage quite low and the effect of the > capacitance > negligible, so the coil may result very good in terms of high inductance, > low self- > capacitance and therefore high Q.The basket weave coil shows a significant > reduction of the proximity effect, so lowering the RF resistance and the > self > capacitance as well. > Criticisms are welcome 73 Cesare > > Cesare Tagliabue I 5 TGC > e-mail: cestag@dada.it > url: http://www.dadacasa.com/i5tgc > > -----Messaggio originale----- > Da: Alan Melia > A: rsgb_lf_group@blacksheep.org > Data: sabato 12 agosto 2000 23.33 > Oggetto: LF: re Basket weave > > >Hi Cesare thanks for that formula. The trouble is it doesnt help with > >multi-pie coils, though I suspect you could just use mutual inductance > >formula. I am hunting in old books of nomographs to see if there is > anything > >in them from the 1920s and 30s. > > > >I have also dropped Reg G4FPQ an e-mail to see if he has anything. > > > >Cheers de Alan G3NYK > >Alan.Melia@btinternet.com > > > > > > From akestelo at bellatlantic.net Sun Aug 13 07:53:17 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:43 2003 Subject: [Lf] [Fwd: LF: Re: Re: Re. LF Aerials etc.] Message-ID: <39967E1C.F63A78AA@bellatlantic.net> vernall wrote: > Christer SM6PXJ wrote: > I have made some changes in my antenna system, which might be of interest > with regard to the recent antenna discussion. > > The antenna system consists of a 21 m vertical and 4 top wires, 20 m each. > The total (feed) impedance is 22 ohms. > This morning I extended one of the top wires from 20 to 55 m. The new wire > goes in a straight line at 18-21 m height. > 15 turns was removed on the loading coil (diam. 450 mm) to get resonance. > My hope was that the feed impedance would go down a bit but this was not the > case. > I have the same feed impedance (and antenna current) as before. > There must of course be a minor improvement due to decreased losses in the > loading coil, but this can't be detected in the measurements made. > > ZL2CA comment: > The implication is that you are reaching the optimum "power factor" of your > "lossy capacitor" in the associated environment. > > I also have a resistive component of around 20 ohms, and have added on some > extra wires, but (after retuning) they do not seem to "earn their keep". > > 73, Bob ZL2CA From akestelo at bellatlantic.net Sun Aug 13 08:31:23 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:43 2003 Subject: [Lf] LF Aerials etc.] Message-ID: <3996870B.28A28D57@bellatlantic.net> LAWRENCE MAYHEAD wrote: > Hi Alan and all contributers to this discussion.I am glad we sorted > out the misunderstanding.I dont know haw much modelling will help,but > who knows! The facts that appear clear to me are:-1) Those with long > top wires achive low loss redistance.2) Those with good ground need > less top wire to achieve low resistanceMy experimens indicate that the > top wire dosnt need to be in a straight line,but it must cover "new" > ground.3 )It is nearly impossible to improve the ground with buried > wires, ground rods etc.a singe good connection to water ,electricity > etc gets you most of the way.4) What is the spray angle (cone as you > suggest) this would gice clue toto best spacing of wire in meandered > configs.Un-answered questions are:-1) Relationship between capacitance > and loss resistance?2) How effective are multiple paralled top wires > compared to extended top wires of the same total length.( I only did > the one experiment,perhaps it need s repeating).3) Is the relationship > between the length of top wire and ground loss linear,or does it > decrease with length(Law of diminishing return)To answer your > questions:- My 3 wire top was about 28m long. the wires were spaced > 0.75m and it drooped,about 14m high at the ends and 13m in centre.I > tried both parallel and meandered configs,there was a small > improvement with one meander config.Which I belived due to some of the > wire acting as an inductance feeding the rest.But the effect was > minimal.2) I measure the loss two ways a)current to the Ant at known > power level,not very accurate. b)Impedance bridge, home made,usual > config with ferrite torroid x former and resistive/capacitive balance > arm.I feed this bridge from the exciter and use an SPM3 level meter as > detector. Many thanks to all who have contributed to this discussion > and to Andy who started it. Cheers Laurie.. From akestelo at bellatlantic.net Sun Aug 13 07:59:23 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:43 2003 Subject: [Lf] basket weave coils] Message-ID: <39967F8B.DE57CAD2@bellatlantic.net> Dave Brown wrote: > John & others > > Design formulas for flat spiral inductors are but one of the many standard > results that can be found in most reference texts. There are several > variations on the basic theme but the prime reference seems to be a Bureau > of Standards Circular No. 74 published back in the mid 1920s. Our old friend > Wheeler seems to have been a significant contributor! > > But like Alan, I have so far failed to find anything specific relating to > multiple pie style windings in any of them. The best summary for inductor > design and associated references I have found so far is Langford-Smith's > Radiotron Designers Handbook, Chapters 10 and 11, covering inductance design > formulas, charts etc and some general discussion on design of many types of > rf inductors. > > 73 > Dave, ZL3FJ > > Original Message ----- > From: john sexton > To: > Sent: Sunday, August 13, 2000 1:13 AM > Subject: LF: basket weave coils > > > Hi all, > > Does anyone perhaps know a formula for calculating the inductance of a > > basket weave coil or a flat cobweb type spiral? > > Couldn't find anything in the RSGB handbook or the LF Source book. > > An internet pointer would do. > > Tnx in advance, > > John, G4CNN > > > > > > > > > > > > > > _______________________________________________________ > > Say Bye to Slow Internet! > > http://www.home.com/xinbox/signup.html > > > > > > From akestelo at bellatlantic.net Tue Aug 15 08:28:23 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:43 2003 Subject: [Lf] LF antenna losses] Message-ID: <39992956.2ADAC8A3@bellatlantic.net> Peter Dodd wrote: > I found the recent discussion on LF antennas, coils and losses most > interesting. My contribution is as follows: > > Early this year I cut back the large conifer hedge at the bottom of > the garden to tidy it all up and found that I had a bonus of around > 0.8amps antenna current. > When I returned from holiday I found the garden had gone wild with > masses of tree and bush growth. Also the maximum current I could get > into the antenna system was back down to 2.5 amps. > Reducing most of this foilage in not practical until later in the year. > > I have now built a new loading coil with some of the Litz wire > obtained from Crawley. The original one used 1mm wire with plastic > insulation, which has a DC resistance of 3.8 ohms. The new coil is > wound with 1.6mm Litz with a plastic insulation giving it a diameter > of 2.8mm. The coil is close wound on a 360mm former made from six > 30mm plastic pipes fixed in a circular manner. The new coil has a DC > resistance of 1.9 ohms. Both coils have an inductance of 2.2mH. The > increase in antenna current, 2.6amps, was disapointing. However this > current could be achieved at a much lower power of 250W rather that > 340W and increasing the power does not increase the current and some > other factor appears to be limiting the antenna current. > I use a multi-tapped transformer to match the antenna to the PA and > there is no sign of overheating anywhere. > > The simple model of the ground loss and radiation resistance in > series does not explain the inconsistencies that we have had reported > on the LF reflector. Most articles on LF antenna systems, such as > 'VLF, LF and MF Antennas' by John Belrose in the Handbook of Antenna > Design consider (naturally) only well engineered commercial sites > rather than suburban gardens! > > Of all my antenna books the Admiralty Handbook of Wireless Telegraphy > (my copy is 1925) is the only one that discusses losses on LF > antennas. At the time LF was the main communication band and the > antenna size was size was restricted. > In this publication the following losses are identified in addition > to ground connection and antenna/loading coil conductor losses: > > Loss in inferior dielectrics - due to hysteresis phenomina in > inferior dielectrics such as wood, concrete, masonry and trees near > the antenna. > > Brushing losses - bluish discharge from sharp points and angles > > Loss by leakage over insulators - dirt and salt build up on insulators. > > Loss by eddy currents in neighbouring conductors caused by > transformer action. Antenna supports should ideally be insulated from > ground or well grounded. Supports connected to earth via a high > resistance path should be avoided. > > > Regards, Peter, G3LDO > > From akestelo at bellatlantic.net Mon Aug 14 10:36:04 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:44 2003 Subject: [Lf] Ooops ? Message-ID: <3997F5C4.649C9AEF@bellatlantic.net> Hello John, Re your article in the Lowdown for August 2000, page 15, my remarks at the AMRAD LF Symposium certainly were not meant to be in any way disparaging to the LWCA. As I recall, I did say something to the effect that "...compared to the efforts of amateur radio operators in Europe, the US side" [i.e., members of the LWCA and AMRAD] "have been involved more in beaconing than actual two-way communications". In addition, during the Symposium, Henry Lee was asked to present his views on LowFers activities, and offered details of various receivers. Incidentally, when I addressed the RSGB LF Forums in England, both in October 1998 and 1999, I uttered there what I believe were very complimentary remarks about the pioneering efforts of LowFers in the US in general, mentioning specifically Lyle Koehler and Bill Bowers. Hoping that this clarifies things a bit :-) 73 Andre' N4ICK From fgentges at mindspring.com Thu Aug 17 16:49:46 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:44 2003 Subject: [Lf] Photographer Needed Message-ID: <399C41DA.436E1BB9@mindspring.com> Hi, I need some photos taken of various pieces of gear we have built. Can someone set up something suitable for book quality photos (lights, diffusers, backdrop etc.)and take some pictures for us over the next few months? Frank -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From akestelo at bellatlantic.net Fri Aug 18 11:11:40 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:44 2003 Subject: [Lf] more of propagation Message-ID: <399D441B.6200100B@bellatlantic.net> V?in? Lehtoranta wrote: > David, > > Yes, skywaves or actually ionospheric waves! > After being few years in CCIR SG6 IWP6/1 group > I learned that original 'skywave' was a kind of > ionospherically reflected (refracted), calibrated > (by IWP6/1) species archived to CCIR databank. > After that I began to talk and write about > 'ionospheric wave', so all the others know that > it was a component that came back to ground level > after making a round trip to ionospheric region. > No layman knows what is a 'skywave' as he/she > thinks sky is something else than ionosphere. > Some people mix it with 'space wave' which in > fact is a combination of direct and reflected > components, usually only above certain freqs. > My English is not good enough to explain... > > Deep angle 'ionospheric' propagation with real > 'ground bounces' is OK if you talk about NVIS > (Near Vertical Incidence Skywave' propagation. > If you talk about long distance propagation, > as most hams are interested in and talking, > this propagating wave with billions of 'rays' > tries to avoid ground as far as possible. > > Deep incidence angle ray pictures have been > produced for decades only because it is very > difficul to draw the whole system to a nearly > correct scale. So, most people are thinking of > a 'skywave' as bouncing between the earth and > one or more of the ionospheric layers while > each of the billion rays tries to avoid the > ground as far as possible - this is due to an > extra attenuation caused by a 'ground bounce'. > > That is the main reason why 'skywave' forecasts > are not usable for certain paths like the EU- > Australia or EU-South Africa paths. Most of the > predictions are still based on 'hops' instead > of ionospherically ducted propagation modes. > > Some of the real researchers have estimated > that 3/4 of so called 'transatlantic propagation' > must be due to some type of ionospheric ducting, > one question is: how often F2 is involved in it. > Has anyone ever confirmed the existence of F1? > > Regards, Vaino, OH2LX > > At 18:21 17.8.2000 -0400, you wrote: > >Hi Vaino What did you mean By "ground bounces" ? Did you mean > >skywaves? > > > >V?in? Lehtoranta wrote: > > > >> The behavior of propagation conditions on low > >> frequency bands is a function of qth, latitude, > >> etc. In our case almost any amount of extra hard > >> x-ray precipitation to the D-region, which is what > >> happens during certain flares, ruins low frequency > >> conditions here. Our main MF test stations have been > >> Norwegian Kvitsoy 1314 kHz and Kemi NDB 373 kHz. > >> They both without exception get weaker or even > >> disappear during even slight solar disturbance. > >> We recorded Kvitsoy and other LF/MF frequencies for > >> decades. SID effects are short lived but eg after > >> the middle of this July Kvitsoy was inaudible here > >> for several days. According to studies the mode > >> on 1314 should be F2 only on short distances, so > >> it is sometimes difficult to decide whether the > >> F2 or E or both were affected by D-region block. > >> 50 MHz people like to talk about transatlantic Es > >> between say UK and NE America but it appears > >> that F2 most certainly must play some part in it. > >> There appears to be some kind of rather regular > >> 'ionospheric ducting' on transatlantic paths. > >> Most talk about 'ground bounces' is misleading. > >> > >> Regards, Vaino, OH2LX > >> IARU Region 1 Auroral studies coordinator > >> > >> At 18:38 16.8.2000 -0000, you wrote: > >> >have been watching the postings on CFH and DCF... > >> > > >> >just what is it you guys are monitoring for, and how are you doing it? > >> > > >> >what programs do I need etc.? or how may I participate? > >> > > >> >david > > |---------------------------------------------------------| > | V.K.Lehtoranta, OH2LX ? 60N33.6 024E58.7 KP20LN74 | > | P.O.Box 50 ? Telephone: +358-9-4173965 | > | FIN-05401, Jokela ? Telefax: +358-9-4173961 | > | Finland ? email: vaiski@dlc.fi | > |---------------------------------------------------------| From akestelo at bellatlantic.net Fri Aug 18 16:59:33 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:44 2003 Subject: [Lf] LF what to expect.] Message-ID: <399D95A5.97C30C61@bellatlantic.net> James Moritz wrote: > Dear Mike & LF Group, > > When atmospheric noise is low, the background noise in UK and > the rest of Europe normally seems to be Loran sidebands - ie. the > rythmic chattering sound that has been likened to 'galloping > horses'. If you can't hear this, and there is no QRN or QRM, then > either you have a deaf receiver, or there is some local noise > source raising the noise floor. If you can hear it - well, that's all you > can hope for! At night, I find the QRN almost always swamps the > Loran sidebands. Being able to hear the Loran sidebands seems > to be a good indicator of adequate sensitivity - LF is nothing if not > noisy! > > At my QTH (Hertfordshire, SE England), the signal from DCF39 is > close to 1mV/m - much stronger than even the local amateur LF > stations. Translating this into s-meter terms, it would be about S9 > plus 20 to 40dB, but of course the actual readings will depend a lot > on antenna, preamp gain, RX sensitivity at LF and so on. It would > be some dB's less in GW, so Mike's s-meter reading sounds about > right. A reasonable expectation for the noise floor on a quiet > morning (no QRN) at my QTH might be 60dB down on DCF39, > perhaps S2 - S4 on Mike's s-meter. The majority of DX amateur > signals are not far above the noise, if not below it. > > Loop antennas may or may not improve the noise situation, > depending on circumstances - but one thing you must watch out for > is that if your LF loop is anywhere near a resonant LF transmitting > antenna, signals and noise will certainly couple from the TX ant to > the loop. This can make a drastic difference at times. Try shorting > or open-circuiting the loading coil on the TX ant, and seeing if there > is any difference. Also, although loops can sometimes give good > noise rejection, they can also be very good at picking up noise > from nearby sources, such as mains or telephone wiring, TV's and > monitors, etc, etc. Experimenting with the loop position is > worthwhile - a few metres can make all the difference. > > Keep up the good work Mike, nice to hear more sigs coming from > Wales. > > Cheers, Jim Moritz > 73 de M0BMU From akestelo at bellatlantic.net Fri Aug 18 11:08:11 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:44 2003 Subject: [Lf] lf propagation Message-ID: <399D434B.E346FE58@bellatlantic.net> V?in? Lehtoranta wrote: > The behavior of propagation conditions on low > frequency bands is a function of qth, latitude, > etc. In our case almost any amount of extra hard > x-ray precipitation to the D-region, which is what > happens during certain flares, ruins low frequency > conditions here. Our main MF test stations have been > Norwegian Kvitsoy 1314 kHz and Kemi NDB 373 kHz. > They both without exception get weaker or even > disappear during even slight solar disturbance. > We recorded Kvitsoy and other LF/MF frequencies for > decades. SID effects are short lived but eg after > the middle of this July Kvitsoy was inaudible here > for several days. According to studies the mode > on 1314 should be F2 only on short distances, so > it is sometimes difficult to decide whether the > F2 or E or both were affected by D-region block. > 50 MHz people like to talk about transatlantic Es > between say UK and NE America but it appears > that F2 most certainly must play some part in it. > There appears to be some kind of rather regular > 'ionospheric ducting' on transatlantic paths. > Most talk about 'ground bounces' is misleading. > > Regards, Vaino, OH2LX > IARU Region 1 Auroral studies coordinator > > At 18:38 16.8.2000 -0000, you wrote: > >have been watching the postings on CFH and DCF... > > > >just what is it you guys are monitoring for, and how are you doing it? > > > >what programs do I need etc.? or how may I participate? > > > >david > > > >QSL VIA E-QSL OR DIRECT....NO BURO > > > >http://www.qslcard.com/qslcard/ > > > >ALL THINGS DIGITAL > > |---------------------------------------------------------| > | V.K.Lehtoranta, OH2LX ? 60N33.6 024E58.7 KP20LN74 | > | P.O.Box 50 ? Telephone: +358-9-4173965 | > | FIN-05401, Jokela ? Telefax: +358-9-4173961 | > | Finland ? email: vaiski@dlc.fi | > |---------------------------------------------------------| From akestelo at bellatlantic.net Fri Aug 18 11:40:21 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:45 2003 Subject: [Lf] Ground loop antennas] Message-ID: <399D4AD4.C73415C@bellatlantic.net> Talbot Andrew wrote: > Many years ago, in the early days of 73kHz someone did experiments on > using ground loops as antennas. This involved walking out a long piece > of wire laid on the ground and connected to a spike at the far end, the > antenna thus consisting of the loop due to the skin depth of the ground > and return current back to the 'home spike'. Intuition says that if > the wire is long enough (say 1km or more), even a spike at the far end > is superfluous, the in-phase radiation current entering the ground loop > via the capacitive element in the same way as the recent discussion on > capacitance hats and lossey earth suggests. By runing out two wires in > dipole fashion, the need for any spike is removed. Since the ground > rod would, as a rule of thumb, have to go down to at least a skin depth > to be effective, that is a lot of bashing in ! > > Presumably this was one of the many areas of experimentation that got > lost when we moved to the current boringly high band of 137. This sort > of antenna will be seriously less effective as frequency rises due to > the reducing skin depth at high frequencies. > > Who was it that used this technique ? I vaguely remember a paper being > written at the time but can find no reference to it now. A different > unrelated project calls. > > Andy G4JNT > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution, > or any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From akestelo at bellatlantic.net Fri Aug 18 11:35:38 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:45 2003 Subject: [Lf] propagation: CFH visible all day] Message-ID: <399D49BA.515B6547@bellatlantic.net> Dave Sergeant wrote: > >From Dave G3YMC > > Alan Melia wrote: > >Hi all, I was somewhat surprised to hear several stations testing and > >calling CQ within +/- 60Hz of 137.000kHz. I am not complaining as this makes > >no difference to any monitoring I do (there are enough gaps for me to see > >what is going on) but as CFH has been 6-8dB above the noise all day from > >about 1130z to about 1700z today it seems like a good way of throwing away > >an S-point, because CFH must be roughly the same strength all over Europe. > > I have not got involved with this thread until now, but there are a few things I would > like to comment on in Alan's recent posting. > > 1. I was listening yesterday here with Steve GW4ALG who was visiting, and we can confirm > that CFH was quite copyable by ear around 1100z. I notice it is also surprisingly strong > this morning (0930z) peaking as high as s6. I also heard one or two stations testing, and > would comment on an increasingly common practice of not identifying when doing such > testing. Surely there is no harm in a quick callsign? As to whether they would have lost > QSOs because of CFH QRM that is debatable, and it is probably the case that the CQers were > more interested in local G contacts than any sort of EU DX, which CFH would not have > interfered with. > > 2. It is important to realise that the reason we don't hear long distance stations on LF > in the daytime is because of D layer absorption rather than anything to do with the F > layer. Hence any increase in CFH in daylight is as a result of a reduction in this D > layer absorption - in the winter when the sun is weak it is common (at least on 160) to > hear stations at considerable distance in the daytime. With a station of the power of CFH > it is reasonable to assume that there is still some residual signal even after the D layer > path loss is included, and although some enhancement in the F layer would also increase > signal levels it is the D layer which is the prime variable. It may be that the effects of > solar storms reduce the daytime ionisation process in the D layer, or it may simply be > normal seasonal variations. Remember this is the first 'season' we have monitored CFH > after their recent TX/antenna changes. I suspect as autumn approaches CFH may well become > more consistent in the daytime. Note also that until sunrise in VE (1000z?) at least some > of the hops are not effected by D layer absorption and the total path loss will be less. > > 3. Although it may be interesting to monitor CFH as an indication of long distance > propogations, it would be an unreserved optimist to believe there is any hope of a > transatlantic QSO on LF in these circumstances. Last winter CFH was peaking 20 over s9 at > night, and we may find it even stronger this year. Perhaps the November tests will give > us a feel as to how much margin we have, but realistically any reception of CFH in the > daytime is of academic interest only. > > 73s Dave > sergeantd@compuserve.com > dsergeant@iee.org > http://ourworld.compuserve.com/homepages/sergeantd From akestelo at bellatlantic.net Fri Aug 18 17:00:32 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:45 2003 Subject: [Lf] Yet another audio analyzer program] Message-ID: <399D95DF.1A81EB8A@bellatlantic.net> DL4YHF@aol.com wrote: > Hello LF'ers, > > For all those who like to play around with audio analyzer software: > There is a new spectrum analyzer (not perfect yet, but stable). > I know there are many other (and most certainly better) programs around, but > maybe some of the features of this new program are useful: > - "contrast" and "brightness" control for the waterfall display. > You may re-paint the waterfall while the analysis keeps "running". > - waterfall and spectrum may be rotated by 90 degrees > - frequency scale may be "mirrored" for LSB receivers > - waterfall may be "scrolled back" without stopping the analysis. > The color palette controls are nice to dig those very weak signals out of the > noise (which we are all looking for ;-). The program runs properly even on > the stone-age 90MHz Pentium which we use at the club station DF0WD. > You may download the software from www.qsl.net/dl4yhf (as long as they don't > kick the 900kBytes off their server hi). > The full source text is also available there (written in C++Builder for > Win95). > > Btw: My apologies to all stations who called me last weekend on 136kHz but > got no reply. The QRM/QRN at DF0WD is terrible these days, I could not even > hear the rattling loran signals ! > > 73's, good luck and hope to *hear* you on 136kHz .... > > from Wolf ( DL4YHF, lf operator at DF0WD ). From akestelo at bellatlantic.net Wed Aug 23 18:07:35 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:45 2003 Subject: [Lf] [Fwd: [Lowfer] Early season propagation...] Message-ID: <39A43D16.7CDC3511@bellatlantic.net> Phil Atchley wrote: > Les et al... > A couple nights ago I was trying out my modified RX-320, just using the > 65 foot Alpha Delta sloper (a poor Lowfer antenna). > > That night I logged 29 beacons from my Merced QTH. (central California) > Admittadly many were Californians but I also logged a number of Canadian, > Washington State, Oregon, Nevada, New Mexico, Idaho, Wyoming and Colorado > beacons, all without any outboard DSP unit. Also noted WWVB very strong on > 60kHz with the same antenna. > > 73 de Phil KO6BB > If it's more than 1dB above the Noise Floor "IT AIN"T DX"! > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Fri Aug 25 09:17:40 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:45 2003 Subject: [Lf] receiving Loop with Litz wire Message-ID: <39A663E3.D868E02@bellatlantic.net> Talbot Andrew wrote: > This weekend just as an experiment, I rewound a small magnetic loop > antenna using 2.5mm (approx) diameter cotton covered Litz wire recently > obtained from the Crawley club sale. The results were impressive to say > the least ! > > Loop 1m square with 22 turns of wire (which was all that I had) - total > wire length 88m > DC resistance 0.75 ohms, inductance 1.66mH, interwinding (stray) > capacitance 260pF > > Frequency Qu > > 140kHz 120 > 78kHz 134 > 12kHz 145 > > The 12kHz result is particularly impressive as a Q of 145 gives an RF > resistance of 0.86 ohms - almost, within measurement error, the same as > the DC resistance. Furthermore, these Q values were in the shack > surrounded by metal, mains wiring etc so should be higher still outside > in the clear. > > A radiator efficiency of -60dB at 137kHz suggests it may just be > suitable for transmitting with low power. However, even 5W drive power > would give many kV across the tuning capacitor, not really ideal with > close spaced cotton covered wire. [...] From akestelo at bellatlantic.net Fri Aug 25 09:18:34 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:46 2003 Subject: [Lf] GPS timed signalling] Message-ID: <39A66419.D35A61FC@bellatlantic.net> Talbot Andrew wrote: > [...] > On another issue, the AD9850 DDS board firmware has now been modified to > allow an external timing signal for chip updata. Now, the controlling > PC can issue frequency / phase update information, and this is not sent > to the DDS until 3us after a 0 to 1 transition on the trigger input. By > using a GPS receiver to generate the trigger pulse, slow PSK and FSK > locked to exact UTC seconds becomes realisable. This removes the need > for clock extraction in any practical link and thus should be capable of > giving a good few more dB in link margin capability. As UTC seconds > pulses derived from even a low cost GPS module is exact to 1us or > better, worldwide, the possibilities are endless............... > > SMT Hell and DFCW software will soon be suitable to allow GPS timing > locked transitions in these modes. > > Andy G4JNT > > -- > The Information contained in this E-Mail and any subsequent correspondence > is private and is intended solely for the intended recipient(s). > For those other than the recipient any disclosure, copying, distribution, > or any action taken or omitted to be taken in reliance on such information is > prohibited and may be unlawful. From akestelo at bellatlantic.net Fri Aug 25 19:26:12 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:46 2003 Subject: [Lf] Coil design] Message-ID: <39A6F284.C675C0DB@bellatlantic.net> "Ashlock,William" wrote: > Guys, > > Some of you coil winders may be interested two Web articles that I just ran > into that explain a lot of the mysteries in designing coils and > transformers, particularly toroids. The author is R. Clarke. The first is > "Magnetism: quantities, units, and relationships" at: > http://www.ee.surrey.ac.uk/Workshop/advice/coils/terms.html#perm (12 pages) > > The second is "Producing wound components" at: > http://www.ee.surrey.ac.uk/Workshop/advice/coils/index.html (14 pages) > > Bill WA > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Sun Aug 27 00:19:11 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:46 2003 Subject: [Lf] Top Loading Vs. Base Loading] Message-ID: <39A888AF.F0C0FE79@bellatlantic.net> Richard Brunner wrote: > This is somewhat apocryphal (doubtful authenticity), but, years ago, when > working with Vince Pinto in up-state New York from Massachusetts, I was > using a fifty foot vertical. When I added top loading, consisting of six 30 > foot wires at about 50?, he said I went up about 10 dB. How 'bout that! > With no top-loading, the effective height is 50% of the antenna height. > With top-loading, effective height is perhaps 80% of the antenna height. > > Top loading coils, in my experience, act more like rf chokes - a bad idea. > You want to get as much rf current as high as possible, and retarding it > with a coil is counterproductive. Think capacitance. (top-loading) > > Richard Brunner, AA1P, rbrunner@gis.net > > ----- Original Message ----- > From: > To: > Sent: Saturday, August 26, 2000 07:22 PM > Subject: [Lowfer] Top Loading Vs. Base Loading > > > > > > > I know that in theory top loading our very short verticals would > > improve radiation resistance. But I wonder if anyone has > > ever compared just how much of a difference this would > > account for. > > > > I have seen an NDB antenna system developed by Nautel called > > the "Polestar" that used a tophat and top loading coil along with > > a small variometer at the base for fine tuning. They claim > > some pretty impressive benefits over a conventional base loaded > > vertical. > > > > Has anyone ever done research into how much of a benefit > > a typical lowfer installation could expect? > > > > Les Rayburn, N1LF > > > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > > send to list!!) Send on list submissions to lowfer@qth.net > > > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Sun Aug 27 10:45:54 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:46 2003 Subject: [Lf] Top Loading Vs. Base Loading] Message-ID: <39A91B92.647B6ACE@bellatlantic.net> Mitch Powell wrote: > >From the Sept 1995 LOWDOWN, Bill Bowers had an article > directly related to your question: > TOP LOADED ANTENNA > > I summarize here :-) , he set up a temporary antenna near > the shop and experimented. Vertical was 36 ft (4 #14 AWG > wires spaced 12") and top hat was 4 ft x 38 ft of 8-#14AWG > wires spaced 6 inches. Copied occasionally 80 mi. away on > low noise days. > > At that point he conducted tests by inserting a loading coil > between the vertical wires and the top hat noting a > significant increase in signal strength "even though there > was only a very small increase in antenna current." > > The loading coil (2.2 mH Q535 wound with Litz wire and > having Amidon 33 rods included) was suspended on the top hat > bus bar and connected in between the bus bar and the > vertical wires. > > It was then necessary to reduce the antenna tuning coil from > 2.65 mH to 1.2 mH. The radiated signal increased and > reception increased to 130 mi., with the 80 mi rcvr copying > on a regular basis. > > Quote"It is interesting to note that even though there was a > significant increase in signal strength there was almost no > increase in antenna current ??"end quote > > He suggests more investigation, and requests any info. > > Les, I hope this information is what you were looking > for.... and not knowing if you had this particular issue I > amd sending it along ( greatly edited - with apologies to > Bill !! ) > > By the way Lyle also did an extensive report on Transmitting > Antennas Page 29 Dec 1993..... and shows apparent benefits > of center loaded transmitting antennas. > > 73 > > Mitch VE3OT From akestelo at bellatlantic.net Mon Aug 28 18:50:47 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:47 2003 Subject: [Lf] Mobile Antennas for Antenna Efficiency Msmts] Message-ID: <39AADEB7.6326AF19@bellatlantic.net> "Ashlock,William" wrote: > Hi Bob and All, > > Just a few words on a subject close to my heart. I've been experimenting on > the Lowfer band for over 4 years but it wasn't until I designed a good > portable receiver two years ago with a multi-range S-meter (call it a > frequency selective voltmeter) that I made real progress in antenna design. > I don't want to imply that antenna design is an empirical process but I > found that it is absolutely necessary to follow up any > theoretical/mathematical design change with an actual measurement that will > give, to a high degree of accuracy, the result of this change. > > My experience has lead to the following conclusions about the needed > receiving equipment: > > Receiver: The performance must be almost as good as the best Lowfer > receivers. The bandwidth should be < 400Hz. The S/N at 1uv should be better > than 20db (for signal checking under 20 miles this could be reduced to > 10uv). The S-meter must be linear responding and must cover at least 3 > decades of signal strength beginning at a full scale reading for a 1uv (10uv > for reduced range) signal. The relative signal strength measurement error > must be < 5% of reading and the absolute accuracy error must be < 25% of > reading. The receiver (and antenna amplifier) should have a good rejection > to AM band signals and any other strong IM generating sources such as Loran > C. Extraneous signals and spurs can lead to time-wasting false readings. > Typical DC (direct conversion) receivers do not meet these requirements. > > Antenna: I recommend a magnetic mounted 1 meter active rather than a loop. A > loop is definitely difficult to manage in many situations including being > outside in foul weather, the usual holding in two hands: the receiver, the > headphones, the antenna, and the usual snarl of wires running between these > - not to mension the need to tune the loop. With the active setup you stay > in your car with all the gear sitting on the seat next to you. > > One negative is that the active antenna requires at least 120ft of tree > clearance for accurate readings but there are many spots, city and rural, > that meet this requirement such as supermarket parking lots, cemeteries, > school grounds, and (safely) off the side of interstate highways. Power > lines on the side of most roads are a problem for both types of antennas. > The calibration of a loop is usually not a simple matter. The calibration of > an active antenna is relatively simple with a standard RF signal generator. > > Any comments/experiences appreciated. > > Bill WA > > -----Original Message----- > From: Bob Roehrig [mailto:broehrig@admin.aurora.edu] > Sent: Monday, August 28, 2000 9:21 AM > To: Don Burns > Cc: lowfer@qth.net > Subject: Re: [Lowfer] Mobile Antennas for Antenna Efficiency Msmts > > On Sun, 27 Aug 2000, Don Burns wrote: > > > What kinds of antennas and receivers are you guys successfully using for > > field strength measurements when checking antenna efficiency? > > -- > > We used some very interesting measurement gear to do this job > > but I'll be danged if I can recall who made it or what it was called. > > Our was a Nems-Clark unit - quite old, it had miniature tubes in it. > The cover contained the loop antenna and it had a calibration osc in it, > otherwise it was nothing more than a regular superhet with a fancy > S-meter. > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Mon Aug 28 18:53:58 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:47 2003 Subject: [Lf] Mobile Antennas for Antenna Efficiency Msmts] Message-ID: <39AADF76.ABC4AA41@bellatlantic.net> Todd Butler wrote: > Don wrote: > > > What kinds of antennas and receivers are you guys successfully using for > > field strength measurements when checking antenna efficiency? > > -- > > > > Years ago as a kid with a ham licnese, I went to work several summers for a > > guy named Walt Kean in Riverside outside of Chicago. He was a broadcast > > consultant and I spent many nights checking field strength at the standard > > measurement spots for AM station directional arrays. It was interesting to > > watch patterns change over time due to new construction of buildings, water > > tanks, etc. We used some very interesting measurement gear to do this job but > > I'll be danged if I can recall who made it or what it was called. > > Having utilized that same process and similar equipment in Indiana, > Connecticut, Wisconsin, Minnesota and Iowa as a broadcast engineer, I can > report the readings are: > > taken at specific locations called "monitor points"..... > > taken with a "field intensity meter" (normally battery powered), highly > calibrated (until someone drops it), and very expensive -- manufactured by > companies like Potomac Instruments in Maryland...... > > two types of readings.....peaks or nulls.....peaks where the signals are > directed toward, nulls where a minimum of signals are pointed to avoid (same or > co-channel) interference..... > > the readings not only change due to construction/renewal -- but can (and do) > change with the seasons, the amount of precipitation (soil moisture), and > vegetation (trees with or without leaves as an example) growth between the > source being read and the location.....time of day (or night) changes the > readings as well....two reasons for this.....skywave propagation from other > stations and power and/or pattern changes required by the Federal > Communications Commission by the licensee..... > > Hope this helps your memories.....the worse readings I ever took were in a > mosquito filled swamp (near the tower) at night with the humidity higher than > the transmitted power in watts..... > > 73, Todd N0NCL 10 - 10 #66816 > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Mon Aug 28 18:55:03 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:47 2003 Subject: [Lf] LF: Leaves] Message-ID: <39AADFB7.930AD093@bellatlantic.net> Dave wrote: > Dear all. > > Whilst in GM this last week I noticed that I couldn't get the 3A antenna > current I got when I was last up there, in early spring. I supposed the > reason to be the amout of leaves on the trees which totally surround ( and > support!) the antenna. > I went in search of the elusive extra 200mA by raising the antenna and > adding more top wire up to the new higher support. Although the top was then > about 3mtrs higher at the centre point and another 6mtrs of wire had been > added, there was no increse in current. > I added a few more earth wires, again a waste of time... > I assume the higher top made an improvement as, the same current into a > higher antenna is better but I couldn't test this. > > I then went for a drive to the coast with a 2.5mtr whip via a tuned pre-amp > feeding the Alinco DX70 which was tuned to DCF39 on 138.8. > I kept an eye on the S meter and noted the following. > Best signal was in open, flat, coutryside. > Trees by the roadside made a big difference (worse). > Being beside a freshwater loch (lake) appeared to make no difference. > A bridge over the estuary was pretty good. > Being near the sea was no better unless you were VERY near. > > No surprises there then..... > I wonder if I had used a magnetic receive antenna, (loop or rod) whether it > would have been so affected by the trees? If not, would a TX loop be better > where there are a lot of trees? > > Dave G3YXM. From akestelo at bellatlantic.net Mon Aug 28 18:56:01 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:47 2003 Subject: [Lf] Antenna Efficiency Msmts] Message-ID: <39AADFF1.10AED79@bellatlantic.net> Johan Bodin wrote: > Hi All, > > PA0SE has designed a field strength meter for the 137 kHz band. > A slight retuning of the front end will make it useful on the U.S. > lowfer band as well. > > A complete description is available at G3YXM's web site: > > http://homepages.force9.net/picks/pa0se.htm > > There is also info on how to construct a pair of Helmholz coils > for calibrating the FSM. > > 73 > > Johan Bodin, SM6LKM > > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Wed Aug 30 23:36:34 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:48 2003 Subject: [Lf] More Field Strength Meters] Message-ID: <39ADC4B1.D1C91D21@bellatlantic.net> "Lawrence R. Ware" wrote: > Gentlemen, > > A few you may know me, I run a hobby business which includes some > refurbing, repair and calibration of older test equipment. > > I've been an active boatanchor collector for some time now and have > published several articles about WWII vintage National radios. [1] > I'm somewhat active over on boatanchors@theporch.com, but due to > work related issues have not been real active for quite a while now. > > I been lurking on this list for several years now and enjoy > reading the mail here. > > For those of you who are serious about measuring signal levels, and > are willing to do your own antenna calculations, or build the fixtures > to calibrate the antennas: > > I would strongly recommend you look into the HP 312 series of > equipment. The HP 312A and the -C (with telco video type connectors) > are quite common on the surplus market with prices for working units > running under $100. > > Frequency response runs from 1KHz to about 18Mhz. > Bandwidth selectable from 3100 to 200 Hz. > Amplitude (calibrated) range from -120 dBm to +23 dBm (50 ohms). > Modes include, AM, LSB, USB and Beat (CW). > > The manuals are quite large, the calibration procedures long, but > not that complex and do not require a ton of odd equipment. > > IMO: These are the best FSL (Frequency selective levelmeters) made, > with mostly gold circuit boards connectors and switch contacts. > They *are* large and quite heavy, and need AC power, but you can't have > everything.... > > [1] I'm working on a book; the history of the National Coil Catacomb > radios. > > -Larry > > # Wayward Electronics, Inc. > # Larry's Home for Wayward Test Equipment & Old Radios (tm) > # P.O. Box 526, Goldenrod, Florida 32733-0526 > # Fluke, HP, and Tek service available when I'm in the mood. > # National Radio Company, Inc. parts and service available more often... :-) > # larry@waywardhome.com - Orlando area, FL - > # 407.679.1597 > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Thu Aug 31 08:10:27 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:48 2003 Subject: [Lf] Ghosts Message-ID: <39AE3D23.B8669FC0@bellatlantic.net> Hello Gang, The possibility of detecting ghosts with an oscilloscope and some extra equipment is described in http://www.picotech.com/ghost.html 73 Andre' N4ICK From akestelo at bellatlantic.net Fri Sep 1 09:05:16 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:48 2003 Subject: [Lf] Mini Cookies Message-ID: <39AF9B7B.C693CB5@bellatlantic.net> MS WORD ALLOWS INTERNET TRACKING COOKIES by Dave Murphy, member@itrain.org Microsoft Word 97/2000 allows graphic images in documents, big deal -- this is old news. And many users also know how to insert hyperlinks into documents, ho hum. But here's a new twist. Word users can also insert a graphic image into a document that's not part of the document but a link to the source graphic on a website (somewhere out on the net). I never gave it much thought -- the bandwidth most users have on their local area networks exceeds their Internet bandwidth, so why not copy the graphic (assuming there's not copyright infringement) down to the network server and link the graphic locally. Sounds pretty neat, until I got thinking about the possibilities after reading a couple of other news reports on this subject last night and this morning. Since a graphic file request made to a webserver would generate an access log entry, the webmaster of the hosting site would be able to tell from which IP address the document's graphic image has been requested. And it's a pretty simple matter to figure out where an IP address originates. Basically, the webmaster can tell which organization is reading the document. I don't want some unknown webmaster tracking which documents I'm reading. It's none of his (or her) business. And since the graphic image could be just a 1x1 pixel, transparent or white image, I may not even notice that the image is part of the document. Imagine the possibilities. Authors can insert tiny graphic images linked back to their webserver and so they can track who's reading their documents (has an loose-lipped employee slipped the 10-year business plan to a competitor?). And the hyperlinked graphic can also be used to generate a cookie entry on the readers' computer. I love technology, but I'm not too sure about all this privacy- busting stuff. I need some time to think it over and talk it through. I'm off to Florida to present a Train the Trainer seminar, and my family and I will work in a week's vacation, too. I'll run this privacy stuff past my Dad while we're visiting. No matter how old we are, some how everything becomes clearer when we talk it over with our parents. See you in a bit over a week. Call for Comments What do you think? Leave your comments on the message center: http://itrain.org/msg/ From akestelo at bellatlantic.net Sat Sep 2 10:09:31 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:49 2003 Subject: [Lf] antennas and top capacitance Message-ID: <39B0FC0B.959452C5@bellatlantic.net> Rik Strobbe wrote: > Hello Marc, > > > For the top capacity ,I'll use 4 X 13 meters wire (25-25-25-25)cm. at > >10meters hight. > > A word of advice : from my experience with multiple topload wires you will > win relative little capacity with only 25cm spacing. I found a kind of > 'optimum' at 80cm spacing, most others with paralllel topload wires have > 0.5 - 1m spacing. > If possible space the wires at least 50cm. If for some reason you are > limited to 75cm space, then you will get about the same result with less > wire (= less weight) when you take 3 wires spaced at +/-40cm. > > Good luck in your attempts to make your first QSO on 136kHz, I remember > getting pretty desperate when I started on this band. I was QRV late March > (1998) and it took until the end of May before I managed to work G3XDV > (what was probably the first 2-way QRS QSO ever). > > 73, Rik ON7YD > -------------- next part -------------- An embedded message was scrubbed... From: Rik Strobbe Subject: Re: LF: Top load Date: Fri, 01 Sep 2000 20:05:52 Size: 2315 Url: http://atanasoff.rf.org/pipermail/lf/attachments/20000902/ce13f36c/attachment.txt From lemaster at pressroom.com Sat Sep 2 17:05:26 2000 From: lemaster at pressroom.com (George Lemaster) Date: Thu Jul 3 13:42:49 2003 Subject: [Lf] LF session at York Hamfest Message-ID: <001701c01519$22eb8540$519508d1@anyone> The York, Pa. Hamfest and Computer Show lists a LF session for Saturday, Sept. 16: 3 PM Room # 1- Low Frequency Reception using Digital Signal processing techniques Further info on the website: http://www.yorkhamfest.org/ -------------- next part -------------- An HTML attachment was scrubbed... URL: http://atanasoff.rf.org/pipermail/lf/attachments/20000902/f877b503/attachment.html From vdetomasi at tiscalinet.it Sat Sep 2 18:14:49 2000 From: vdetomasi at tiscalinet.it (Vittorio De Tomasi) Date: Thu Jul 3 13:42:49 2003 Subject: [Lf] [Fwd: [HCDX] Re: Hard-Core-DX digest, Vol 1 #52 - 18 msgs] Message-ID: <39B12779.B562D59B@tiscalinet.it> just found this on HCDX mailing list: maybe it is useful to somebody. Vittorio -- ************************************************************************* Vittorio De Tomasi ik2czl@amsat.org http://www.weaksignals.com "Wir muessen wissen; wir werden wissen" (David Hilbert) -------------- next part -------------- An embedded message was scrubbed... From: "Guy Atkins" Subject: [HCDX] Re: Hard-Core-DX digest, Vol 1 #52 - 18 msgs Date: Tue, 8 Aug 2000 08:14:45 -0700 Size: 6329 Url: http://atanasoff.rf.org/pipermail/lf/attachments/20000902/9c152f43/attachment.txt From riese-k3djc at juno.com Sat Sep 2 20:45:17 2000 From: riese-k3djc at juno.com (Bob RIESE) Date: Thu Jul 3 13:42:50 2003 Subject: [Lf] LF session at York Hamfest Message-ID: <20000902.195305.-4281.3.riese-k3djc@juno.com> UHHHHHHHH this will be a rather provincial presentation and more in line with the WONDERS of LF HI. Dick USG is making up a slide show and I am going to have some LF receive gear on site it will be a challenge to see what we can see with my ribbon cable loop. As I will have my 187 beacon running and only 2 miles from the hamfest it should be copied and we hope to have the beacon NF from southern York County on and if the propagation gods permit a copy on AMRAD. may end up with some wave files of good signals to play through Spectran as well Should be fun and the intent is to stir up some local interest After all Dick is the Monster Loop Guy, With 2 being built in the area there is interest there. Bob K3DJC On Sat, 2 Sep 2000 16:05:26 -0400 "George Lemaster" writes: >The York, Pa. Hamfest and Computer Show lists a LF session for >Saturday, Sept. 16: >3 PM Room # 1- Low Frequency Reception using Digital Signal processing >techniques > >Further info on the website: > >http://www.yorkhamfest.org/ From W3HMS at aol.com Sun Sep 3 02:37:21 2000 From: W3HMS at aol.com (W3HMS@aol.com) Date: Thu Jul 3 13:42:50 2003 Subject: [Lf] LF session at York Hamfest Message-ID: Bob....sounds FB...sorry I will miss it...who is building the 2nd Monster Loop....you? 73, John,W3HMS From akestelo at bellatlantic.net Sun Sep 3 10:30:53 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:50 2003 Subject: [Lf] bentonite for grounds Message-ID: <39B2528D.4A03CE7@bellatlantic.net> > Subject: [HCDX] Re: Hard-Core-DX digest, Vol 1 #52 - 18 msgs > Date: Tue, 8 Aug 2000 08:14:45 -0700 > From: "Guy Atkins" > Reply-To: hard-core-dx@hard-core-dx.com > To: > References: <200008080750.e787o9q07270@kotalampi.com> > > Patrick, > > If you can locate a supply of the mineral called Bentonite, it makes an > excellent ion-rich (and non-corrosive) backfill for ground rods and > grounding systems. Professional antenna installations and electrical > substations use Bentonite for lowering the resistance to earth. > > I have read that Bentonite is sold at animal feed stores; it is used as an > additive to cattle & pig feed. Also, ceramic supply stores sometimes carry > Bentonite, as it is a special clay used by potters. > > During a vacation one year, I got my initial supply of Bentonite directly > from a refinery in Wyoming where they mine the stuff... they gave me some > bags of Bentonite free because the bags were slightly ripped and they > couldn't sell them. > > To use the Bentonite, you dig a hole eight inches or more in diameter, > perhaps three feet deep (post-hole digger helps), and suspend the ground rod > in the middle. Put in a few inches of the powdered or crushed Bentonite, > water it thoroughly (it swells up tremendously with water), and then add > another layer. Water that layer, and continue with water-soaked layers of > Bentonite until the hole is filled up. > > The Bentonite absorbs the water, expands, and holds the ground rod very > tightly in the center. Because of the expansion and Bentonite's conductive > qualities, a lower resistance path to ground is achieved. It's sort of like > using an eight-inch diameter ground rod at your site. The Bentonite never > drys out, as it is "hydrophilic" and absorbs moisture from the soil to > remain hydrated. > > If you do a web search on the term "bentonite" you'll come up with a lot > more information about this mineral. Besides improving ground systems, it is > used as a colloidal (suspension) product for everything from vinyl plastics > to chocolate(!) to cosmetics. Also, Bentonite, in a highly refined form, is > the key active ingredient in disposable baby diapers (I'm not kidding!). I > know this trivia because Bentonite mining is one of the industries in the > region of Wyoming my wife grew up in. > > Here in Bonney Lake, WA, our soil is very rocky, ancient glacial debris > from Mt. Rainier. Even though we live on a small island and are surrounded > by water, the soil is still very dry and rocky. Bentonite surrounding my > ground rods has improved the directionality of my impedance-matched, > terminated 175 ft. longwire. There was a noticeable improvement in > directivity to Papua New Guinea and Irian Jaya after improving the ground > with Bentonite. > > I also use the same ground for K9AY electronics (the head unit), although I > don't know if this is really helping. > > BTW, there was a IEEE paper written some years ago about Bentonite grounds. > The careful measurements and comparisons they did showed clearly that > resistance-to-ground was lowered when Bentonite was used. This method is > clearly preferred over adding various salts to the soil... Bentonite won't > corrode the ground rod nor harm the soil or surrounding vegetation. > > Guy Atkins > Bonney Lake, WA > USA > > ----- Original Message ----- Message: 17 > From: mwdxer@webtv.net (Patrick Martin) > Date: Tue, 8 Aug 2000 00:23:06 -0700 (PDT) > To: am@nrcdxas.org, hard-core-dx@kotalampi.com > Subject: [HCDX] Grounding > Reply-To: hard-core-dx@hard-core-dx.com > > Hi: > > As many of you know, I have several beverages and antennas I use. Here > on the Northern Oregon coast we generally get a lot of rain 60-100 > inches a year. This Summer has been a "dray" one to say the least. Does > anyone know what the best type of grounding I could use? Right now I am > using a series of several rods (copper pipes) with #14 bare copper wire > connecting them. It isn't all that easy to put 8-10 foot rods in the > ground, so I use 4 foot ones. Most of the year the pipes are under > water. Oh course in the dry part of the Summer the grounding is in very > sandy soil. I notice this Summer when we get a bit of drizzle or light > rain, the noise level goes down and the antennas work better, as they > should. What would be a resonable ground system that would work pretty > well even when the soil is dry? Also should I increase the number of > rods at all grounding points, including the matching transformer > grounding points and the termination points? I am just trying to make > the system work better, as we are trying to do. Getting that 1/2 DB > signal can make the difference of logging the rare catch. Thanks. > > 73s, > > Patrick From akestelo at bellatlantic.net Sun Sep 3 11:42:07 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:51 2003 Subject: [Lf] G3YXM 136kHz Pre-amp Message-ID: <39B2633F.CA3624C5@bellatlantic.net> G0MRF@aol.com wrote: > I've had some PCB's made for Dave's excellent little bandpass filter and > pre-amp. ( Rad Com Sept 2000 and Dave's web site) > > Although we all have our receive systems optimised, this may be of interest > to anyone starting out on LF. > > It's available as a complete kit of parts or as an assembled tuned and tested > board. > > The single sided PCB measures apx 44 x 34 mm. http://www.g0mrf.freeserve.co.uk/preamp.htm -------------- next part -------------- An embedded message was scrubbed... From: G0MRF@aol.com Subject: LF: G3YXM 136kHz Pre-amp Date: Sun, 3 Sep 2000 08:37:43 EDT Size: 1776 Url: http://atanasoff.rf.org/pipermail/lf/attachments/20000903/8af638ce/nsmailD4.txt From akestelo at bellatlantic.net Mon Sep 4 13:51:13 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:51 2003 Subject: [Lf] Noise source Message-ID: <39B3D300.D75BCC83@bellatlantic.net> For those of you traveling through the Tysons Corner area (Northern Virginia, just outside the I-495 Beltway at 9 o'clock), there is an experiment that awaits your investigations. If you drive in a NW direction on Old Courthouse Road and approach its intersection with Rt. 123, you will see Howard Avenue on your right. At that point, you will find, should you be listening on AM, either to WMAL 630 or to WTOP on 1500 KHz, that your reception is almost totally obliterated by a AM noise source. Questions: a) what is the source? b) should someone complain to the FCC? (IMHO, if we, amateur operators, do not chase sources of noise, we will soon be unable to do anything of SW, because ISDN, ADSL etc. will have taken over the airwaves) 73 Andre' N4ICK From akestelo at bellatlantic.net Mon Sep 4 19:50:54 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:51 2003 Subject: [Lf] Top Loading coil] Message-ID: <39B4274D.E54A178E@bellatlantic.net> Mitch Powell wrote: > Hi Les: > Moved coil to top of vertical wire/junction of > top-hat. Checked locally ( 5 miles ) and used > receiver S-Meter to do quick check. > Coil at mid-point - reading S4.3 > Coil at top - reading S 4.7. > Very subjective reading as you can imagine, but I > was really waiting for report from 120 mile rcvr. > He indicates an 3 dB improvement in the signal level > at that distance. > > Tuning: Using the variometer, the tuning for minimum > SWR, is much less sensitive ( i.e. tunes much easier > with no sharp peak - as when coil is low down ) > The antenna current is unchanged. The "base" coil did > not have to be changed when I went from mid-point to top. > If you remember last time - coil moved from bottom to mid- > required about 10% increase in "base" coil requirements. > > Transmitter DC current remains same as 'mid-point'. > > ISo - top coil position gives an apparent 3dB increase, and > I have apparently reached the maximum antenna current with > present configuration and leafy tree configuration I have. > > 73 > Mitch VE3OT (QRSS 137.780- 24/7) > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From riese-k3djc at juno.com Mon Sep 4 22:21:11 2000 From: riese-k3djc at juno.com (Bob RIESE) Date: Thu Jul 3 13:42:51 2003 Subject: [Lf] Re: AMRAD Beacon Message-ID: <20000904.212621.-5253.1.riese-k3djc@juno.com> They are on with a watch on the sky and shut down for storms [ lots this year ] I also believe that only one is on I have been monitoring very little lately and I believe the signal is down from its winter high I dont know if they rolled up there radials for the summer,,, could have Hi I referred a copy of your note to the AMRAD reflector see if they have a better answer than my guess ; ] Bob From: "Mitch Powell" To: riese-k3djc@juno.com Date: Tue, 05 Sep 2000 15:38:48 +0100 Subject: AMRAD Beacon Message-ID: Hello Bob: saw you recent e-mail re: PA hamfest.... and you referred to AMRAD beacon - can you tell me if AMRAD beacon is still on and being received ? Have not copied this Summer, and keep trying so though maybe they have shut down for Summer QRN/lightning. Thanks 73 Mitch VE3OT ( QRSS 137.780 24/7) From akestelo at bellatlantic.net Tue Sep 5 00:08:28 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:51 2003 Subject: [Lf] Re: Noise source References: <39B3D300.D75BCC83@bellatlantic.net> <004a01c016ce$c5561140$c39508d1@anyone> Message-ID: <39B463AB.89160095@bellatlantic.net> I believe that if it interferes with reception of a _local_ broadcast station, then the FCC should step in. But I am no specialist in this matter. Possibly Paul Rinaldo could give his opinion. Andre' *************************************** George Lemaster wrote: > Andre' > Yes, very interesting. The noise seems to be very strong in front of 1880 > Howard Ave on 600kHz, particularly at the left end. At the rear of the > building noise is also very strong and seems to have an additional 60 Hz > component. (UPS?) The noise seems to continue fairly strong going south on > Old Courthouse near Tycon 1 building, on that side of Old Courthouse, pehaps > one block away, but does not seem to be coming from Tycon 1 building. It is > stronger near the street. It could be carried on the overhead telco wires, > but where the telco trunks split and go across Old Courthouse the signal > seemed to drop off. It did not seem to be on the powerline wires. > > Could be DSL, it did seem to have a data type sound, but I don't know what > DSL sounds like. > As to the FCC , I suppose there is no problem in informing them, but will > they be at all interested in our complaint when it is not affecting us > directly, that is, at our station location or home? > 73 > George. > > ----- Original Message ----- > From: Andre' Kesteloot > To: Tacos, AMRAD ; lf, AMRAD > Sent: Monday, September 04, 2000 12:51 PM > Subject: Noise source > > > For those of you traveling through the Tysons Corner area > > (Northern Virginia, just outside the I-495 Beltway at 9 > > o'clock), there is an experiment that awaits your > > investigations. > > > > If you drive in a NW direction on Old Courthouse Road and > > approach its intersection with Rt. 123, you will see Howard > > Avenue on your right. At that point, you will find, should > > you be listening on AM, either to WMAL 630 or to WTOP on > > 1500 KHz, that your reception is almost totally obliterated > > by a AM noise source. > > > > Questions: > > a) what is the source? > > b) should someone complain to the FCC? > > (IMHO, if we, amateur operators, do not chase sources of > > noise, we will soon be unable to do anything of SW, because > > ISDN, ADSL etc. will have taken over the airwaves) > > > > 73 > > Andre' N4ICK > > From akestelo at bellatlantic.net Tue Sep 5 11:05:38 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:52 2003 Subject: [Lf] Cue Cat ? Message-ID: <39B4FDB2.FA123372@bellatlantic.net> Has anyone on this reflector tried the new bar code reader ("Cue Cat") that can be obtained free of charge from Radio Shack, and is used to access directly relevant information on the web? There are several steps about "activating your software" that make me suspicious as to whether this will also open somewhere a mega database of the stuff I might be interested in... Andre' From whansell at cox.rr.com Tue Sep 5 12:18:42 2000 From: whansell at cox.rr.com (William Hansell) Date: Thu Jul 3 13:42:52 2003 Subject: [Lf] Cue Cat ? In-Reply-To: <39B4FDB2.FA123372@bellatlantic.net> Message-ID: <000301c0174c$93d902c0$accf1c18@cox.rr.com> I picked up a Cue Cat last week. As I'm sure most of you are aware they are free from any Radio Shack store. It only took a few minutes to plug it into my mouse port and plug my mouse into the Y-connection on the Cue Cat cable. Before you go to Radio Shack go to their web site and print out a coupon for a free 2001 catalog. Make sure you pick up a free catalog with the free Cue Cat. To get up and running you need to load some software off a CD ROM that comes with Cue Cat and then go to the Cue Cat web site and register. They want the usual information, name, address, etc. They also ask if you would like to give more information as part of a marketing survey. Seconds later an e-mail comes in with a registration confirmation code. I have used the Cue Cat to read bar codes out of the new Radio Shack catalog. A web page pops up with technical details on the item and information on availability and discounts. I also tried it with a Cue code in the Sunday paper (not Radio Shack). It worked fine. I'm sure that any company involved with this technology is keeping track of web site visits and purchases but that's no different than what they were doing before Cue Cat. Cue Cat does take the leg work out of finding the web page your looking for. There is a master Cue Cat web site. I don't know if that site is involved in every Cue Cat web transaction and capable of building a total profile of your web shopping habits. It is certainly possible. You may have to choose between convenience and privacy. How many of us have totally disabled all internet cookies on our machines? Do you know what all of those cookies are doing? Bill The device works as advertised. -----Original Message----- From: lf-admin@amrad.org [mailto:lf-admin@amrad.org] On Behalf Of Andre' Kesteloot Sent: Tuesday, September 05, 2000 10:06 AM To: Tacos, AMRAD; lf, AMRAD Cc: Kesteloot, Lawrence Subject: [Lf] Cue Cat ? Has anyone on this reflector tried the new bar code reader ("Cue Cat") that can be obtained free of charge from Radio Shack, and is used to access directly relevant information on the web? There are several steps about "activating your software" that make me suspicious as to whether this will also open somewhere a mega database of the stuff I might be interested in... Andre' _______________________________________________ lf mailing list lf@amrad.org http://www.amrad.org/mailman/listinfo/lf From akestelo at bellatlantic.net Tue Sep 5 15:20:37 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:52 2003 Subject: [Lf] Cookies ? References: <000301c0174c$93d902c0$accf1c18@cox.rr.com> Message-ID: <39B53975.7C948525@bellatlantic.net> William Hansell wrote: > You may have to choose > between convenience and privacy. How many of us have totally disabled all > internet cookies on our machines? Do you know what all of those cookies are > doing? You do not want to disable the cookies, as some servers get nervous if you do. Instead, a) use a text editor and cut out all the stuff in your cookies files, b) write a short phrase to that file ("I love chocolate" is a good possibility) c) save it d) now, change the attribute (ATTRIB) of the cookies file to make it a "read only" file. e) Then the cookies, which remain in RAM until the end of the session, have nowhere to go when you turn off your computer :-) 73 Andre' From mthompson14 at yahoo.com Thu Sep 7 13:19:51 2000 From: mthompson14 at yahoo.com (Mike Thompson) Date: Thu Jul 3 13:42:52 2003 Subject: [Lf] SUBSCRIBE Message-ID: <20000907191951.1793.qmail@web115.yahoomail.com> SUBSCRIBE __________________________________________________ Do You Yahoo!? Yahoo! Mail - Free email you can access from anywhere! http://mail.yahoo.com/ From akestelo at bellatlantic.net Sat Sep 9 10:23:50 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:53 2003 Subject: [Lf] Electrophonic Sounds" Message-ID: <39BA39E6.93453C7E@bellatlantic.net> Fascinating, IMHO Andre' N4ICK *************************************** mailbox:/C|/Program Files/Netscape/Users/akestelo/mail/Inbox?id=39BA0F06.E926C6C5%40ex-pressnet.com&number=94113880&part=1.2 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://atanasoff.rf.org/pipermail/lf/attachments/20000909/8591766a/manmade_meteors.html From akestelo at bellatlantic.net Sat Sep 9 18:26:11 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:53 2003 Subject: [Lf] USB Port Message-ID: <39BAAAF3.8E7B9C2@bellatlantic.net> In the IEEE Spectrum for September 2000, page 90, mention is made of the FT8U232AM, a single-chip USB UART. It can be used to upgrade old RS232 design. Apparently one "simply" replaces the RS232 level converter IC with the above chip, and uses the free drivers. This chip is made by FTDI in Scotland. The US distributor is Saelig. Details from http://www.saelig.com The chip cost $3 in quantities. Nothing is said about samples. A demo board is available for $85 73 Andre' N4ICK From esanders at erols.com Sat Sep 9 21:54:36 2000 From: esanders at erols.com (Nan and Sandy Sanders) Date: Thu Jul 3 13:42:53 2003 Subject: [Lf] RE: Electrophonic Sounds" Message-ID: <01C01AA2.973486C0.esanders@erols.com> also try http://www.eskimo.com/~billb/hum/hum1.html Sandy ---------- From: Andre' Kesteloot[SMTP:akestelo@bellatlantic.net] Sent: Saturday, September 09, 2000 9:23 AM To: lf, AMRAD; Tacos, AMRAD; Gould, John W Subject: Electrophonic Sounds Fascinating, IMHO Andre' N4ICK *************************************** From akestelo at bellatlantic.net Sun Sep 10 02:34:35 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:53 2003 Subject: [Lf] UK/Canada LF Crossband ! Message-ID: <39BB1D6B.8F243C23@bellatlantic.net> John Currie wrote: > A crossband qso between The UK and Canada was completed at 0008Z on > 10 SEPT 2000. G0MRF was operating on 135.71 kHz and VE1ZJ was > operating on 14,043 kHz details wl follow tmw . Tnx for great effort > David 73 de John VE1ZJ From akestelo at bellatlantic.net Sun Sep 10 12:53:48 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:53 2003 Subject: [Lf] [LF: crossband qso G to VE] Message-ID: <39BBAE8C.DFFC0CBF@bellatlantic.net> John Currie wrote: > Dave had surprisingly strong signal intp FN95 Cape breton Island , Nova > Scotia Canada His freq was 135.711 kHz > 1 Weak dashes were first observed at just after 2205Z > 2 2218 my sunset 128.9 was S-3, 138.9 was S-2 > noise was extremely low > 3 2233 128.9 S-4.5 138.9 S-1 lot of dashes it kooked > like G0MRF was coming across the pond > 4 2240 S-5 128.9 S-3 > 5 2245 solid copy on G0MRF > 6 crossband qso 135.71 kHz to 14043 completed 10 sept 0008Z > G0MRF 135 VE1ZJ 14 mHz > 7 Daves signals were O copy I could see every dot and dashat 0000 > z on the 10th. 8 > 8 At that time 128.9 S-6 138.9 S-6 S-7 represents > field strength of 100 micro volts per mtr > I would estimate Daves sigs at a little less than S-0 at least > 36 db below DCF39. > After 0100 sigs dropped off to m copy and by 0250 they were t > and fading. I did not see them on spectrogram agn > 9I believe the sig to noise ratio dropped because qrn went up > and I think we hsd qrm from the Marathon stn The qrm had a spectral > line at 135.782 kHz. > 10 The interfering stn began to fade and by 0245 had M copy > agn 128.9 was S -8.5 138.9 S5.5 > 11 noise however was now about 4 S-units higher than at sunset > Did not see David after 0250 on 135.71 > > I am amazed that u in EU can set up a remote tx site in > only 2 or 3 hours > > with such good results Congrats and thanks all for helping me with > receiving tips > John VE1ZJ From akestelo at bellatlantic.net Sun Sep 10 18:06:10 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:54 2003 Subject: [Lf] VE1ZJ / G0MRF / VE1ZZ- LF QSO Message-ID: <39BBF7C1.F0D1D840@bellatlantic.net> G0MRF@aol.com wrote: > Hello All. > > Thanks for all the best wishes to John and me passed via the reflector in the > past 24 hours. > > My operation on 9 / 10 Sept was a continuation of an attempt to construct > and test a loaded dipole for 136kHz. Despite building a scale model at > 2.5MHz, Saturday night's experiment also failed. I managed to get a > reasonable match but discovered that all the current was flowing around the > link coupling coil with non actually making it to the elements. Oh well! > > Equipment / site / antenna. > > The location for G0MRF was a West London tower block in Feltham, just South > of Heathrow airport. The 15th story, top floor flat, is the home of Sean > Griffin 2E1AXK. We were joined by Tony Fell G7DGW. > The dipole was 're-worked' to give a standard sloping antenna with two wires > each 250 feet long. The angle between the two was about 60 -80 degrees. The > ends of the wires were about 30 feet above ground and tied off with 50 lb > breaking strain fishing line. The earth was connected to the plumbing system > of the building. The antenna was of coarse fed from the top, at about 160 > feet AGL. > > Loading was a combination of fixed inductor in series with a variable coil. > Matching was achieved by earthing the base of the fixed coil and tapping a > few turns up. > Once this was wired up I used an amplified DDS source to drive a modified > version of the reflectometer bridge published in rad-com 9/2000. With this > little circuit ( 3 x 50R resistors and a transformer) the antenna loading > and matching was completed in less than 3 minutes. > > The transmitter was a converted Decca unit with a DC input of 58 Volts at 15 > Amps. > Antenna current peaked at 7.2 Amps. Drive was a 'SM6LKM' DDS with 0.25Hz > steps at 136k. > > John Larry and Jack on the other side of the Atlantic were all aware of the > schedule and frequency for the tests. After about an hour John called to > confirm he could see the signals and would I QSY up 1Hz to clear a Loran > line. No problem. > > The crossband QSO was then completed without problem with 'O' signals on both > 135.711 and 14.043 MHz. > > Interestingly I then reduced power to just 400W DC input, or about 320W TX > output and John reported an M signal. Even allowing for the large antenna I > believe this shows that Many UK / EU stations will be able to make the > transatlantic path this winter. > > In another telephone conversation, John reported that Jack VE1ZZ was > transmitting on 136.5kHz using a long horizontal antenna ('OLB style) > Unfortunately, Jack does not have a computer for QRS. > Using Spectran with about 40Hz across the screen we looked very closely for > Jacks 10 second dashes. After about a minute we spotted several dashes, > broken by static, about 8Hz above 136.500. > In a phone call to Jack I asked are you transmitting now 8Hz off frequency? > No said Jack, my counter says its only 7 Hz...........I'll settle for that. > > In one evening: 136kHz signals from the UK heard in Canada and CT > A QSO crossband to 20m G/VE > 136kHz signals transmitted from Canada heard in the UK > > With a real sense of achievement and elation I arrived home only to be > confronted by a family tragedy. Consequently, today, Sunday, is a day of > mixed emotions and I hope those of you who have been kind enough to send me > personal e-mails will accept both my apologies and this general reply. > > 73 > > David > > From akestelo at bellatlantic.net Mon Sep 11 15:45:16 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:54 2003 Subject: [Lf] Observations on the N.Atantic path] Message-ID: <39BD283B.62F4E874@bellatlantic.net> Alan Melia wrote: > In the week running up to Dave's expedition to the tower block, and after > some discussions with Vaino, I have been monitoring CFH through the night > with the strength recorded by an ADC and plotted as a graphical record. The > set-up is far from perfect, but it yielding some interesting results. > > In general the comment that Dave G3YMC makes is true the best conditions for > receiving CFH are usually in the hours between 0330z and 0530z (at present), > when it can often be 3dB or so stronger than earlier in the night. By > coincidence, this was not the case on Saturday/Sunday when CFH rose to a > good level at 2300z and maintained it for about 2 hours before some fades > set in. after about 0230 the strength declined and some very deep fades > occured. There were returns to normal peak strength but only for short > periods of a few minutes. > > Observations by Brian in Portugal and Mike G3XDV have confirmed my thoughts > that the quietest period for us, in the East, is just on and just after > dawn. I also noted that John reported a quiet period for a couple of hours > after dusk. This set me thinking. Stations on the edge of the ocean will see > different levels of noise as the shadow sweeps in. In Europe, as the dark > shadow of dusk sweeps in it brings skywave QRM and QRN from all the rest of > the continent ...1500kms to the east....all occupied. When dawn sweeps in, > the skywave qrm from the east is attenuated by D-layer absorption (?) and we > have a quiet period until the local noise sources start up. On the west > coast of N.America and Canada the dusk will bring up the skywave signals > from Europe up over 'daylight' noise levels, as there are only fish for > 3000kms due East there is not much QRM. It is not until the shadow has swept > about 1000kms inland that the skywave noise begins to build up, lasting > probably to after dawn. > > If this hypothesis has any substance, it means that it may be best to > transmit East to West at 2300z and West to East at 0500z to make best use of > the low noise periods at the receiving station. We may have to work out a > 'protocol' for doing that, which is acceptable as a two way contact. > Fortunately some nights show CFH at good strength at both times > ...Friday/Sat, and Sun/Monday being recent examples. I had thought it > possible that the unsettled nights with the deep fades were correlated to > high Geomagnetic activity, but the relationship is by no means clear. > > Well the path has now been trodden....go to it fellas. > > Cheers de Alan G3NYK JO02PB > Alan.Melia@btinternet.com From akestelo at bellatlantic.net Mon Sep 11 13:00:13 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:54 2003 Subject: [Lf] Spectrum Lab Version 1.4 available] Message-ID: <39BD018D.A15980E4@bellatlantic.net> DL4YHF@aol.com wrote: > Hello group, > > The new version of Spectrum Lab (V1.4) is now available at > www.qsl.net/dl4yhf, including the full source code. I moved the software > archive to a new site, hope the links are ok on my homepage. > > I added a few features to the spectrum analyzer+filters, found a few bugs, > removed some of them :-) > The (N)-th order IIR or FIR filter now works surprisingly well. You can > design any combination of lowpass, highpass, bandpass or notch filter if you > need and save the filter design in a file. > > To Christer, SM6PXJ: I added a simple "frequency converter". You may try it > for your 17.2 kHz IF but I'm not sure if the soundcard's anti-aliasing filter > will not filter the wanted signals out. Enter the frequency for the local > oscillator on the "Component Window". > > To Petr, OK1FIG: Hopefully the "Automatic Screen Capture"-feature now works > like in your EasyGram. I played with the new feature a little but didn't try > the timer's wrap-around at midnight... maybe you can. > > 73's, cul from Wolf (DL4YHF). From akestelo at bellatlantic.net Fri Sep 15 13:34:53 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:54 2003 Subject: [Lf] Use of Spectogram Message-ID: <39C24FAC.EB9DBBCE@bellatlantic.net> Rik Strobbe wrote: > John wrote>I'm not good at Spectrogram. I need all the help i can get. > Question > >I have been leaving my AGC on in fast mode Is this a mistake? > > Hello John, > > If you have strong signals within the RX bandwidth it is best to switch the > AGC off (otherwise the AGC triggered by the strong signal might 'modulate' > weaker signals. If you cannot switch the AGC off then the second best > solution is to attenuate the incoming signal, as long as the band-noise > (QRM/QRN) is stronger than the receiver noisefloor you will not loose > sensitivity. > Even if you can switch off the AGC it can be worth adding some attenuation > to the incoming signal in order to improve the IM behaviour. I am using a > 11.5m high and 23m long inverted-L (tuned to 137kHz) as antenna and a > Kenwood TS440 as RX. I found out that I have best results with a 20dB > attenuator, the external noiselevel is still far above the RX-noisefloor > and I got rid of a lot of 'birdies'. > > 73, Rik ON7YD > > (hpe to work u 2nite .... ..) From akestelo at bellatlantic.net Sat Sep 16 00:11:06 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:54 2003 Subject: [Lf] Re: Query about LF References: <3.0.5.32.20000915184057.00a89820@127.0.0.1> Message-ID: <39C2E4CA.D671F1B6@bellatlantic.net> Re your questions about LF. a) transmissions: The European Amateur Radio operators have been at it for longer than we have, hence if you are interested in transmissions techniques, I would recommend "The LF Sourcebook" published by the Radio Society of Great Britain, and available from the ARRL. b) reception only: the LowDown is an excellent publication dedicated mainly to LF reception, low power beaconing. etc. c) AMRAD has a fair amount of expertise. We publish the AMRAD Newsletter, we run continuously 2 LF beacons on 136,745 and 136.750, and you may want also to attend our meetings: we meet every Saturday noon for lunch in Fairfax Virginia and the second Thursday evening of each month in McLean Va. All meetings are informal and technical. (No rules of order etc.) Details on http://www.amrad.org d) equipment: if you only want to listen to stuff (beacons, transatlantic transmissions, ???, etc.) you will probably need a preamp in front of your receivers. Most receivers are fairly "deaf" below 250 KHz. Another thing that helps is a "e-field probe" or e-field antenna, aka "active whip antenna" with a high impedance preamp up on the mast, away from your roof. Hope this helps 73 Andre' N4ICK From akestelo at bellatlantic.net Sat Sep 16 17:15:02 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:55 2003 Subject: [Lf] Loran Lines] Message-ID: <39C3D4C6.E344110B@bellatlantic.net> john sexton wrote: > Hi Guys, > Yet more about Loran-C. After a lot of searching down false trails, I have > finally found the definitive page for a complete list of these stations > world-wide: > http://www.megapulse.com/table.html > > There are 4 chains (groups of stations with a common Group Repetion Rate - > one Master and up to 6 secondaries) on the North Eastern Atlantic side and 3 > on the North Western Atlantic side. There are many other chains in the US, > the Mediterranean, Russia including Chayka and world-wide. Interestingly > most stations are "Dual rated", i.e. transmit in two chains. So the > impression that I had reported that Sylt was stronger for me is wrong. > Lessay transmits as Master on its own chain and as a Secondary on the Sylt > chain, and vice versa. > > I list below the stations participating in each chain: > > North East Atlantic > Chain Stations GRI > Lessay Lessay, Soustons, Sylt 6731 > Boe Boe, Jan Mayen, Berlev?g, Ejde 7001 > Sylt Sylt, Lessay, Vaerlandet 7499 > Ejde Ejde, Boe, Jan Mayen, Vaerlandet 9007 > > North West Atlantic > Chain Stations GRI > North East US Caribou, Nantucket, Seneca, Carolina Beach, Dana 9960 > Canadian East Coast Caribou, Nantucket, Cape Race, Fox Harbor 5930 > Newfoundland East Coast Cape Race, Fox Harbor, Comfort Cove 7270 > > The list of line frequencies for the sub-band 135.7 to 136 that I gave last > night for the Canadian side was only for the Canadian East Coast chain. I > have now calculated a complete list for the whole of our band for all 3 > North West Atlantic chains. If you would like a copy please ask, or > calculate your own using Excel and the formulae given by Andy. Remember to > double the GRI before dividing into 100000. > > 73 John, G4CNN > > _______________________________________________________ > Say Bye to Slow Internet! > http://www.home.com/xinbox/signup.html From akestelo at bellatlantic.net Sat Sep 16 17:16:09 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:55 2003 Subject: [Lf] UK AM broadcasters concerned about ADSL Message-ID: <39C3D508.D8FA485A@bellatlantic.net> > >From the Times, September 16 2000 > > BUSINESS NEWS > > BT plans meet with interference > BY RAYMOND SNODDY, MEDIA EDITOR > > BRITISH TELECOM'S plans for a nationwide rollout of > high-speed Internet services has come under an > unprecedented attack from the entire UK radio industry, > which fears that the planned network will cause > interference to millions of radio listeners. > > The BBC and commercial radio have both written to the > Government expressing concern with the planned rollout > after testing by their engineers found that high-speed > ADSL lines - used for fast Internet access and > video-on-demand services - could cause interference with > both medium-wave and long-wave services. > > Apart from local services, two of the UK's national > commercial networks, Talk Sport and Virgin Radio, are > broadcast on medium wave. One of the BBC's most > successful radio services, Radio 5 Live, which broadcasts > news and sport, is also a medium-wave service. Radio 4 > long wave could also be be hit. > > In an unprecedented move, the Radio Authority, the > regulatory body for commercial radio, and the BBC have > united to complain to the Government about the potential > danger of interference. > > The problem is most acute where an ADSL telephone wire > comes into a home, potentially affecting AM radio > services nearby. Engineers believe that people living > nextdoor to a home with an ADSL line could also be > affected. > > Broadcasters, who insist they are not opposed to the > spread of ADSL services, are particularly annoyed at the > alleged attitude of BT. > > They believe that the potential for interference could be > removed at minimal cost by slightly reducing the power > used for the ADSL service, or by fitting a simple "choke" > to the wire, costing an estimated 30p each. BT, the > broadcasters claim, is refusing to adopt either measure. > > Kelvin MacKenzie, chairman of Talk Sport, yesterday > said: "I think their position is wholly unreasonable. It is > another case of the huge corporation kicking the little > guy in the stomach. This could be a very big issue for us." > > A senior BBC executive said: "I think this is a real issue. > We are very concerned." > > But BT said that it did not believe there was a problem. It > said the ADSL equipment was manufactured to a world > standard and that extensive market research after a > commercial ADSL trial in West London had thrown up no > evidence of interference. From dlwilson at erols.com Sat Sep 16 20:17:07 2000 From: dlwilson at erols.com (David L. Wilson) Date: Thu Jul 3 13:42:55 2003 Subject: [Lf] Loran Lines] In-Reply-To: <39C3D4C6.E344110B@bellatlantic.net> Message-ID: <4.1.20000916191141.00931120@127.0.0.1> At 04:15 PM 9/16/00 -0400, you wrote: >john sexton wrote: > >> Hi Guys, >> Yet more about Loran-C. After a lot of searching down false trails, I have >> finally found the definitive page for a complete list of these stations >> world-wide: One of the fun things to do with LORAN-C is to turn your AGC off and feed the audio to an oscilloscope vertical, select an appropriate horizontal scan rate and then triggering the scope with precisely a LORAN-C chain repetition rate. By strobing the scobe this way, you freeze on the display the chain with the rate selected and can see the individual stations in the chain. The other chains move across the display and depending on the phospor decay rate and adjustments may almost be eliminated (especially if you take a photo). From akestelo at bellatlantic.net Sun Sep 17 11:49:02 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:55 2003 Subject: [Lf] UK AM broadcasters concerned about ADSL] Message-ID: <39C4D9DD.7D849BE6@bellatlantic.net> Dave Sergeant wrote: > >From Dave G3YMC > > Stewart Bryant wrote of an article in Saturday's Times about ADSL: > >BRITISH TELECOM'S plans for a nationwide rollout of > > high-speed Internet services has come under an > >unprecedented attack from the entire UK radio industry, > >which fears that the planned network will cause > >interference to millions of radio listeners. > > There was an extensive article in IEE Communications journal about a year > ago which analysed the whole issue of xDSL and its potential for > interference with braodcast, amateur and other services. I have mislaid the > original article but I remember it pointed out that the AM broadcast service > operates in a different way in the USA, where transmitting stations tend to > be located in city centres, than in Europe where they tend to be in remote > locations away from cities. This was pointed out may result in more > interference problems in Europe than in the USA where ADSL has been in use > for some years. It may now be that these problems are being experienced, > and presumably if the RA takes a tough view it could spell big problems for > BT. At the moment ADSL is only available in London and the other large > cities but is scheduled to expand in the next year or so. > > I noted with amusement, in the discussion of amateur interference, that ADSL > was not thought to be an issue here as amateurs do not transmit below > 1.8MHz! In fact the ADSL baseband starts around 400kHz so perhaps the > effects on Radio 4 and 136 will not be a problem - but only time will tell, > and interference in general is slowly getting worse. > > 73s Dave > sergeantd@compuserve.com > dsergeant@iee.org > http://ourworld.compuserve.com/homepages/sergeantd From akestelo at bellatlantic.net Sun Sep 17 11:51:04 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:56 2003 Subject: [Lf] more on broadcasters concerned about ADSL] Message-ID: <39C4DA57.DBE7DB0D@bellatlantic.net> Andy Talbot wrote: > The broad spectrum of opposition mentioned has really come about because of > the 'Expert Group' originally set up between all interested parties when > Power Line Telecomms was being proposed. The group was started by the RSGB > getting in touch with the RA and interested parties and as everyone knows, > PLT has fortunately, and largely as a result of the groups working, been > killed off in the UK - although various overseas groups are still thinking > about it. I am a member of this group, not in an RSGB/Amateur radio > capacity, but to protect Defence radio interests which in some ways are > similar to the amateur ones. > > The work of the group has now moved onto specifying emissions of any wired > data systems that may radiate and at the moment are considering the band > 150kHz to 1.6MHz which of course covers ADSL. There is a discrepancy > between radiated field levels that proponents of ADSL are prepared to commit > to, and what the radio users in that part of the spectrum, chiefly BBC and > Aeronautical Navigation, are prepared to accept as to what constitutes an > interfering level. When this issue is finally settled, radiation at > frequencies in HF will need considering and we will need to be more vigilant > than ever to protect the amateur bands. > > Andy G4JNT From akestelo at bellatlantic.net Mon Sep 18 11:02:51 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:56 2003 Subject: [Lf] [Fwd: LF: Transatlantic tests] Message-ID: <39C6208A.1E7AB896@bellatlantic.net> Mike Dennison wrote: > John, VE1J wrote: > > I think I agree wth Alan 8 or 10 second dashes it would be much > > easier to tell us from the enemy(LORAN in this case). > > Beware! > > It is true that longer dashes will give you a better S/N ratio and is > therefore a good thing to do. It will especially improve immunity to > short term QRM such as static and random noise. It will not improve > the immunity to Loran - quite the reverse as the averaging will add > up the Loran pulses and will make good solid lines. > > The other problem is that the improvement is =only= realised when > either the selectivity is increased (use Spectran for this), or the > averaging is increased (on recent versions of Spectrogram use an > averaging setting one or two less than the number of seconds per > dot). This will mean that stations sending 3-4s dots will no longer be > readable - the dots and dashes will merge into each other. > Furthermore, the scroll speed will have to be altered. In other words > the two speeds are incompatible. I suggest that any use of long dot > lengths is scheduled in advance so that =everyone= can adjust their > speeds. > > It would also help if someone could coordinate frequencies as > happened with the VA3LK tests. There have already been instances > of two people selecting the same frequency, and I notice that last > night I picked what seemed be a clear channel only to find someone > on exactly the same frequency when I closed down. Perhaps one of > those who have already made it could take this on. I am happy to do > it if no-one else wants to, and can post the frequencies on my web > site. > > Lastly, is VE1ZZ doing any transmitting tests? It will be just as useful > to check the reverse direction. It will also give a chance for those > without big transmit signals to achieve something. If so, it would be > preferable to avoid times when the big signals are on the air. > Perhaps 0400-0500 UTC, or specify a day of radio silence in Eu. > > Mike, G3XDV (IO91VT) > http://www.lf.thersgb.net From dsp at hifidelity.com Mon Sep 18 16:03:45 2000 From: dsp at hifidelity.com (Steve Dove) Date: Thu Jul 3 13:42:56 2003 Subject: [Lf] York Hamfest LF Seminar Message-ID: <39C66711.7374CF45@hifidelity.com> Hats off to Dick, WA3USG, and Bob, K3DJC, for a fine introductory seminar on LF at the York Hambonefest last Saturday. Nice video presentation on their two stations, and plenty of discussion with hands-on bits of gear etc. Also present was Ted WN3F, he of the "NF" lowfer beacon on 172.4kHz from York County. The two most salient points brought across were "It's difficult NOT to make stuff work down there . . ." and that Spectran-like FFT analysis was an essential, not an option, for reception. Cheers, Steve From akestelo at bellatlantic.net Mon Sep 18 16:19:28 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:56 2003 Subject: [Lf] Transatlantic Tests/Frequencies/Loran] Message-ID: <39C66AC0.FD6E83CA@bellatlantic.net> Yet another British amateur received in Canada, and with only 350 watts this time Things are looking good. Andre' James Moritz wrote: > Dear LF Group, > > Extremely pleased to be received in Nova Scotia by VE1ZJ on > Saturday night. This was done with the usual 350W and a piece of > wet string, so I hope this means that many others with quite > modest stations will have a good chance of success also. Being in > the right place at the right time seems to have been as much a > factor as equipment in the successes there have been so far, so > keep trying. I think that propagation is still far from optimum, so > further reaches of Europe should be quite feasible as the winter > progresses. > > Has anyone heard from VA3LK about how his listening tests earlier > in the week went? I fear he may have had the worst of the > propagation upsets there have been. > > As far as frequencies go, I think some sort of plan is a good idea. I > think the problem with having 2 windows as suggested is that the > top end of the band is also used for inter-european QRSs; It will be > hard for european stations listening for transatlantic signals when > there are several local QRS stations in the same window. Perhaps > setting aside a small segment purely for intercontinental listening > near the top of the band would be an idea? > > It is also convenient to have a 'test' segment on the band for > running power into antennas and doing measurements, etc. I have > used around 135.95kHz for this - I think the bottom edge of the > band was originally set aside for this in the 'unofficial band plan' > that has been around for a while - but this obviously needs another > look now. > > Thanks to G4CNN for preparing the lists of Loran frequencies. I did > a survey of Loran (and other) lines I could see at my QTH, at the > top and bottom band edges. The figure after the frequency is the > strength on a scale 1-5. These should be within +/- 0.5Hz: > Bottom edge (Hz): > 135700.3 5 > 135704.5 2 > 135707.8 3 > 135711.3 3 > 135715.3 5 > 135718.0 4 > 135722.6 5 > 135724.5 1 > 135730.0 2 > 135731.3 2 > 135737.8 4 > 135745.0 4 > 135750.0 1 > 135751.2 2 > 135752.5 5 > 135760.0 4 > 135764.9 3 > 135767.3 3 > 135774.8 2 > 135778.0 1 > Above about 135780, we run into SVX. > Top end: > 137706.2 3 > 137711.5 1 > 137713.5 2 > 137720.9 2 > 137725.0 1 > 137728.3 3 > 137731.4 1 > 137736.0 2 > 137743.3 4 > 137745.0 2 > 137747.0 2 > 137748.4 3 > 137749.5 1 > 137750.9 4 > 137752.5 2 > 137754.9 5 > 137758.2 4 > 137764.0 5 > 137765.2 1 > 137773.1 1 > 137778.4 1 > 137780.3 2 > 137788.0 2 > 137795.4 3 > 137798.3 1 > The majority of these appear to be from the Lessay and Sylt Loran > chains as expected (frequencies at intervals of 7.4227 and > 6.6676Hz). The range 137743 - 137755 is a bit of a no-go area, > with lots of closely spaced lines. > > I also checked around 136.508kHz, where VE1ZZ's beacon is, I > believe: > 136495.5 1 > 136502.7 4 > 136504.7 1 > 136510.0 1 > 136518.0 3 > > So VE1ZZ's frequency is reasonably clear. > > Will be interested to see how other's observations compare. > > Cheers, Jim Moritz > 73 de M0BMU From akestelo at bellatlantic.net Wed Sep 20 10:14:10 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:57 2003 Subject: [Lf] Exploding MOSFETS] Message-ID: <39C8B822.E6C434B0@bellatlantic.net> Tom Boucher wrote: > Wil > > I cannot claim to have been anywhere near as scientific as Andy in > investigating my exploding PA devices, but I have also recently > installed a variometer instead of the tapped coil used before, and my > Class D PA now appears to be quite happy and runs quite cool at the > kilowatt input level (85 volts at 12 amps). I have also changed the > matching arrangement from a tapped grounded coil system to a simple > series loading coil. I adjust the variometer for maximum antenna current > at a low power level, then wind the Tx up to maximum. Unlike Andy, my > long wire comes directly into the shack so I don't need any remote > tuning arrangement. (Makes my hair stand on end though.) > > I do not have any SWR protection but I do have over-current protection > (using Dave YXM's Hall Effect device idea). > > I have taken to installing only 2 IRFP450s instead of 4 in parallel > push-pull. That way I only blow up 2 instead of 4! However I am on my > last pair of IRFP450s and next time am going to install some STW20NB50s > which are better rated and cheaper than the IRFP450. (500 volt, 0.27 ohm > on resistance, 20 amps continuous, 80 amps peak) > > Not sure if the above is any help. I have yet to transmit using long > duty cycle modes so may still have a problem. > > 73, Tom G3OLB From fgentges at mindspring.com Wed Sep 20 01:09:34 2000 From: fgentges at mindspring.com (Frank Gentges) Date: Thu Jul 3 13:42:57 2003 Subject: [Lf] York Hamfest LF Seminar References: <39C66711.7374CF45@hifidelity.com> Message-ID: <39C8387E.9FB186FB@mindspring.com> Hi all, I was off in Alaska and missed the York Hamfest and the LF presentation. Glad to see our AMRAD work spreading so well. Congrats to the York crowd. Frank Steve Dove wrote: > > Hats off to Dick, WA3USG, and Bob, K3DJC, for a fine introductory > seminar on LF at the York Hambonefest last Saturday. > > Nice video presentation on their two stations, and plenty of discussion > with hands-on bits of gear etc. > > Also present was Ted WN3F, he of the "NF" lowfer beacon on 172.4kHz from > York County. > > The two most salient points brought across were "It's difficult NOT to > make stuff work down there . . ." and that Spectran-like FFT analysis > was an essential, not an option, for reception. > > Cheers, > > Steve > > _______________________________________________ > lf mailing list > lf@amrad.org > http://www.amrad.org/mailman/listinfo/lf -- Frank Gentges K0BRA, ex AK4R, W3FGL Check out our LF web page at From akestelo at bellatlantic.net Wed Sep 20 15:43:33 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:57 2003 Subject: [Lf] Poor waveform at output transmitter] Message-ID: <39C90555.34ADCD90@bellatlantic.net> Dave wrote: > Wil / Dick / Tom and all. > > As many amateurs seem to suffer from FET > blow-ups due to fatal voltage and/or current > peaks caused by proper TX loading only at the > fundamental frequency I wonder whether it would > be wise to insert a diplexer between TX output > and tuning/loading system; a combination of a > lowpass filter feeding the aerial circuit and a > highpass filter feeding a resistor that absorbs > the power in the harmonics. That might save > FET's. It won't help of course when the loading > at thefundamental frequency is wrong, causing > FET overload.What do you think? > > I tried the diplexer idea and it didn't seem to have any > advantage. As one of the country's greatest destroyers of > fets I can make a few suggestions. Recently I have not had > any blow-ups atall by following these rules.... (I'm > touching wood!) .1. Always match the antenna to 50 Ohms > and operate the TX via an SWR bridge so that you know the > match is good before increasing power. The output filter > is designed for 50 Ohms and will transform other > impedances into possibly dangerous loads on the TX output > stage. .2. Check the drain waveforms on the fets with a > 'scope. They should be clean, usually looking like a > square wave with a sine shaped peak. Lots of spikes or > "fuzz" is bad news and can be cured by fitting a Zobel > network between the two drains. i.e. across the primary of > the output transformer. This network consists of a 10 to > 27 Ohm large wirewound resistor in series with a 10nF > pulse-rated C like the ones used in the LPF. Use 27Ohms > with 75V rail or above and 10 Ohms with 30 - 40V > rails. .3. Add a fast-acting protection circuit operating > on overcurrent and bad SWR which cuts the drive, relays > are too slow! See my circuit or G0MRF's for ideas. I am > convinced that the trip has saved my 4 x IRFP450 rig on > numerous occasions.If you use a 4013 as the phase-splitter > / final divider stage, this can be forced to send both > outputs high by putting a high on the set and reset pins. > After an inverting driver stage this means both fets are > turned off within a half-cycle. Good luck and may your > fets last a long time! Dave G3YXM. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://atanasoff.rf.org/pipermail/lf/attachments/20000920/526b18bd/attachment.html From akestelo at bellatlantic.net Tue Sep 19 15:36:40 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:58 2003 Subject: [Lf] Internal Variometer analysis, Oh Dear !! Message-ID: <39C7B238.F1B81970@bellatlantic.net> Rik Strobbe wrote: > Hello Andy, > > The 250uH coil in the shack and the 1500pF of the coax will act as > impedance matching : > > -----/\/\/\----+----- > L | > R1 C === R2 > | > ---------------+----- > > The formulas are : > XL = Q.R1 > XC = (R1^2+XL^2)/XL > R2 = R1.(1+Q^2) > > But the limit for a 'stable' transformation is R2 > 2.XL > In your case R2 = +/- 100 Ohm (antenna impedance) and XL = 214 Ohm (250uH > at 136kHz), so this condition for a 'stable' transformation is not > fullfilled and the slighest change of L or C will have an huge effect on R1 > (= impedance seen by the transmitter). With the values you have R1 changes > from 50 Ohm at 135kHz to 5000 Ohm at 152kHz. I wouldn't worry too much > about the 'notch' near 270kHz as the lowpass filter at the output of your > TX will 'isolate' that. > A lower L/C ratio (put some C in parallel to the coax) might give better > results but will transform antenna impedance to lower values. > But even if you get the transformation more 'stable', changing L (in order > to adjust antenna resonance) will alway affect the impedance transformation. > Maybe a low-Q 'double matching' network (with 2 L's and 2 C's) will give > better results. > Anyway, I suggest to simulate the matching before spending some more > power-FETs. As long as you have a huge peak or notch close to 136kHz your > FETs are not save. > > 73, Rik ON7YD > > At 12:15 19/09/00 +0100, you wrote: > >Just done a network analysis on the antenna matching system mentioned in > >my previous Email and this sheds quite a bit of light on the exploding > >PA problem. > > > >The network analysed was as follows : > > > >250uH variometer (series input element) > >1500pF to ground (representing coax cable capacitance) > >4.8mH loading coil, > >270pF antenna capacitance > >100 ohms loss / load resistance > >(The last three in series, shunting the coax capacitance to ground) > > > >Results : > > > >135.1kHz Zin 53 ohms resistive, close to its actual measured > >value. > >152kHz A Very sharp resonant peak with the network appearing as > >an OPEN circuit at the input > >269kHz Very sharp resonant peak and network Zin appears as a > >SHORT circuit. > > > >You may recognise this situation as similar to the parallel / series > >resonance of quartz crystals - the network topology is similar. > >The 152kHz open circuit shouldn't give a problem as there should be no > >energy at this frequency if the amplifier is unconditionally stable. > >However, the 269kHz peak is very close to the second harmonic of the > >drive frequency, meaning the Tx is terminated by a short circuit at 2.F. > > > >Now, this shouldn't be a problem for a current drive PA stage at its > >fundamental, and a push pull PA should cancel out second harmonic > >energy anyway. But instinct says this IS the problem -- circulating > >currents within the PA perhaps which would be why they didn't show up on > >the monitoring circuitry or on the scope. Thinking about it, I did see > >some even harmonics present in the RF current but didn't take any notice > >at the time, and there was a significant visible 2nd harmonic component > >to the output from the low power test amplifier too - but its > >significance hasn't struck until now. > > > >It looks like the values for variometer and coax cable were just an > >unlucky combination to give the second harmonic resonance, so I guess > >some careful analysis and a more complex matching network are needed - > >perhaps with a low pass filter at the PA output to isolate harmonic > >impedances will make for a safer matching network. > > > >Also, the comment about a few percent increase in coax voltage / current > >was a lie. According to the above analysis, the values actually rise by > >4.3 times in this network (which just happens to be the factor > >SQRT(loading coil / variometer) so the coax feed needs replacing with > >UR67 or better for high power. The phase of the volatage / current on > >the coax is -70 degrees so we have the classic tuned feeder situation > >where feed losses contribute disproportionatly to overall loss. Initial > >calculations were obviously flawed ! > > > >Alternatively, go back to the first design with a variometer built into > >the loading coil, but it would be nice to be able to tune from indoors. > >A motor on the outside coil variometer perhaps or remotely switched taps > >? > > > >Andy G4JNT > > > > > >-- > >The Information contained in this E-Mail and any subsequent correspondence > >is private and is intended solely for the intended recipient(s). > >For those other than the recipient any disclosure, copying, distribution, > >or any action taken or omitted to be taken in reliance on such information is > >prohibited and may be unlawful. > > > > From akestelo at bellatlantic.net Thu Sep 21 10:17:47 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:58 2003 Subject: [Lf] More on E field vs. H field Message-ID: <39CA0A7B.94A22167@bellatlantic.net> >From the UK Newspaper "The Guardian" New cancer link to power lines Paul Brown. environment correspondent Thursday September 21, 2000 New evidence that high voltage power lines cause cancer by making particles of pollution stick to people's lungs has been uncovered by a team from Bristol University. The team's research shows that car exhaust particles get an electrical charge from overhead power lines that makes them "sticky" - giving people living close to the lines two or three times the average daily dose of potentially damaging pollutants in their lungs. David Henshaw of Bristol University said the discovery is the missing link that shows how power lines can cause cancer clusters - something the global electricity industry has spent millions of pounds researching without finding a conclusive answer. His work is supported by Dr Alan Preece at the Bristol Medical School, whose independent research in the west country showed that people living up to 500 metres downwind of power lines have a 29% greater chance of contracting lung cancer. This finding matches the area where "sticky" particles from car exhausts drift downwind of power cables. [...] the whole article can be read at http://www.guardianunlimited.co.uk/Distribution/Redirect_Artifact/0,4678,0-371089,00.html From akestelo at bellatlantic.net Wed Sep 20 10:15:21 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:58 2003 Subject: [Lf] LF: Poor waveform at output transmitter] Message-ID: <39C8B869.686E047@bellatlantic.net> Dick Rollema wrote: > To All from PA0SE Like at many stations the output signal > (both voltage and current) of my transmitter looks > terrible (4 x IRF520 parallel/pushpull class B). On a > dummy load it is very similar to a sine wave.The > transmitter is connected to tap on the loading coil, a few > turns up from the bottom.The aerial current is clean, due > to the selectivity of the aerial circuit. The voltage at > and current through the FET's stays within the rated > limits as long as I can resist the urge to increase the > supply voltage from 30 to 40V (aerial current rising from > 2.0A [1.6A when it rains] to 2.5A). At 40V the situation > becomes critical and detuning the aerial system causes a > FET (always one) to act like a crowbar. Probably the > maximum permissible current or voltage is exceeded so I > have to blame myself. As many amateurs seem to suffer from > FET blow-ups due to fatal voltage and/or current peaks > caused by proper TX loading only at the fundamental > frequency I wonder whether it would be wise to insert a > diplexer between TX output and tuning/loading system; a > combination of a lowpass filter feeding the aerial circuit > and a highpass filter feeding a resistor that absorbs the > power in the harmonics. That might save FET's. It won't > help of course when the loading at thefundamental > frequency is wrong, causing FET overload.What do you > think? 73, Dick, PA0SE -------------- next part -------------- An HTML attachment was scrubbed... URL: http://atanasoff.rf.org/pipermail/lf/attachments/20000920/eaa855e3/attachment.html From DK8KW at compuserve.com Sat Sep 23 12:24:00 2000 From: DK8KW at compuserve.com ('Geri' Kinzel, DK8KW) Date: Thu Jul 3 13:42:58 2003 Subject: [Lf] OK1FIG QRV with *BIG* signal tonight Message-ID: <200009231124_MC2-B468-6119@compuserve.com> Dear LF-enthusiasts, tonight (September 23, 2000) Petr, OK1FIG will be transmitting according to the following schedule: Begin of 1st transmission at 22.00 UTC on 135.755 kHz Begin of 2nd transmission at 04.00 UTC on 135.755 kHz QSX 14042 kHz or 10106 kHz. VE and W: stay tuned ... I believe this signal *will* make it accross. Petr is using a 150m high Marconi vertical antenna and has a booming signal into Europe currently. He is 46 dBmicroVolt/m here, around 430 km away, which makes his signal the strongest ham-signal I have ever heard on LF. Best 73 es gl Geri, DK8KW (W1KW) From DK8KW at compuserve.com Sat Sep 23 15:15:43 2000 From: DK8KW at compuserve.com ('Geri' Kinzel, DK8KW) Date: Thu Jul 3 13:42:58 2003 Subject: [Lf] VE1ZJ: OK sked-change tonight confirmed ... Message-ID: <200009231415_MC2-B475-D28E@compuserve.com> Hello John, >Hi Geri I'm glad you got amessage about possible qrm to CFH. If you could >communicate again I would prefer if he could start both transmission periods >earlier the first at 2130 and the second at 0300 If you can't get hold of him >don't worry about it tnx . When will you have 1 watt ERP I saw M0BMU and I >think he has only 300 mw ERP . > 73 de John VE1ZJ< I got hold of Petr again, it was a little bit difficult because he had quite a high QRN level (and I still have only about 150 mW ...), but he confirmend the changed sked-times for tonight (September 23, 2000): 21.30 and 03.00 UTC he will transmit on 135.755 kHz. Currenlty they signed off and will get a little rest. Best 73 es gl for 2nite Geri, DK8KW (W1KW) P.S.: wtill working on my 1.5 kW PA ... will not be ready before November ... but who knows ... From akestelo at bellatlantic.net Sun Sep 24 10:56:16 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:59 2003 Subject: [Lf] LF: OK1FIG, the record so far Message-ID: <39CE0800.49B4067F@bellatlantic.net> "'Geri' Kinzel, DK8KW" wrote: > Petr and John, > > also congrats from my side for the currend distance world-record on LF, > according to my calculations (JO70ND ==> FN95XM) even 5389 km! > > Best 73 > > Geri, DK8KW (W1KW) From akestelo at bellatlantic.net Mon Sep 25 11:04:14 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:59 2003 Subject: [Lf] Window Me Message-ID: <39CF5B5D.85BD50@bellatlantic.net> WINDOWS ME, AN EASY INSTALL by Dave Murphy, member@itrain.org I sat down this weekend and got more than eight hours of uninterrupted time to work with Microsoft's update to consumer-side of Windows. Windows Millennium Edition (WinMe) gets a big thumbs up from me. I came up with a few concerns, but nothing major. I recommend the operating system (OS) for new installations, and I even installed three upgrades on top of Windows 98 (first edition). All installations worked great once the prompts were followed, the "next" buttons clicked, and the kinks worked out. My recommendations: 1. Opt for WinMe over Win98 on any new PCs you purchase, even if you've already got Win98 systems in your network. 2. Consider upgrading faster workstations that are currently running Win98 to WinMe. First, seek the advice of your IT advisor. This step is not for the less-knowledgeable (especially those who think they're knowledgeable). What I did: I upgraded three Win98 (first edition) workstations connected to a set of Linux file servers and peer-to-peer network. All workstations accessed at least one of the servers and all shared their hard drives with one another. All workstations shared a high-speed digital connection to the net. I also installed a copy of WinMe on a brand new disk. This workstation then accessed one of the Linux servers, the other workstations, and the Internet router. This station also shared it's disks with the other Windows workstations. It took about 90 minutes to install and tweak. The new installation took about 25 minutes on a 500 MHz system with 128MB of RAM. Configuration and tweaking took about another hour. The system was ready for use in less than 90 minutes. This is about the same time as a similarly-configured new Win98 installation. The upgrades took about 25 minutes to install and about 30 minutes to configure. All of the preexisting Win98 configurations were retained, and I tinkered with the new options of WinMe. My experience is that most technical installers and all non- technical users run WinMe straight -- without any of the performance and security tweaks I employ. If you fall in this group, figure less than an hour for an upgrade -- time to cut the shrink wrap, read the pamphlet, and such. Typing in the serial numbers was a pain. I found this step more cumbersome than with previous versions. What I found. The systems that were running at 200MHz and above picked up a bit of speed. The 350MHz system with 64MB of RAM runs sluggishly. It's definitely noticeable. So much so that I'm thinking about reinstalling the previous disk image, thereby returning to Win98. WinMe is a fun version. It's got neat features that I haven't yet tested. When I do, I'll report them in this e-zine. All systems work well after two days. The Handspring Visor's PalmOS hotsync program, the Adaptec CD burner software, web browsers, Eudora, both Microsoft Office 2000 and the old Office 97 seem to work. McAfee VirusScan 4.x and Norton Utilities 2000 are fine. I was actually surprised that the Win98-WinMe upgrades worked well. I've never had good luck with OS upgrades. I'll give it some time, and I'll let you know if my opinion changes. But for now, don't hesitate to pick up a new PC with WinMe installed. But don't go out and upgrade your existing Win98 system without checking with each of your application and hardware vendors to ensure you'll have full compatibility. I spent quite a few hours over the last two weeks reviewing all my upgrade details before I started ripping shrinkwrap. Call for Comments What do you think? Leave your comments on the message center: http://itrain.org/msg/ From akestelo at bellatlantic.net Mon Sep 25 11:44:17 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:59 2003 Subject: [Lf] Antennas, swamps and such Message-ID: <39CF64C0.5F2E845D@bellatlantic.net> Pierre Thomson wrote: > Hi Mike, > > I used to wonder the same; it seems like AM broadcast stations are > often built in swampy areas, and they seem to do well there. But if > you think about the difference between AM broadcast and Lowfer > antennas, you will see a big difference. A typical AM antenna is a > full quarter wave, or approaching it. The feedpoint impedance is 37 > ohms or so, almost purely radiation resistance. A decent ground is > important, but a few ohms here or there make little difference. > > A Lowfer antenna, on the other hand, is less than 1/100 wavelength > long, and its radiation resistance is under 1/10 ohm. The impedance > of the tuned system is mostly a combination of losses, and one of > the big ones is ground loss. Here a few ohms make a huge difference > to the overall efficiency. From my own experience, it seems that any > moisture in the system increases loss; my signal drops way down in > rain, and doesn't fully recover until the ground is dry. Based on this, I > would say that a fresh water swamp would not be ideal. > > Regards, > Pierre Thomson > KA2QPG / RI From akestelo at bellatlantic.net Mon Sep 25 11:45:47 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:59 2003 Subject: [Lf] more on swamps and such] Message-ID: <39CF651B.300FE69E@bellatlantic.net> David Riley wrote: > The jury is in and the results are printed in FCC tables in the form of > ground conductivity curves. > > Salt Water is 5000 micromhos per meter conductivity and believe me you can > hear best out on the ocean by far. Transmit too. > > Jungle and treed area is worse case. > > Rule of thumb: > > If you are on a salt water marsh like WBZ-AM or in Brant Rock where the > first radio voice broadcast took place in 1906 then a vertical with radials > is for you. One way to beat poor soil is to make the radials 'resonant'. > This you may do by using insulated wire radials slightly shorter than a > quarter wave and 'loading' while watching RF current in that leg. > > If you are on a rock mountain or useless conductivity soil like sand then > think about using a loop or balanced antenna. KDKA-AM Pittsburgh uses a > 'Franklin' which amounts to a center fed half wave up in Allison Park on the > rocks. I use full wave loops on 160 and 80 and hav'nt seen a better > performer in 50 years. ( more quiet on receive too ) > > Alas it is true, I=E/R evan at A.C. > > 73s de Dave - 1A From akestelo at bellatlantic.net Mon Sep 25 15:51:10 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:42:59 2003 Subject: [Lf] [Fwd: [Lowfer] swamps and such] Message-ID: <39CF9E9E.DBBFEC93@bellatlantic.net> Bob Duckworth wrote: > I agree on both counts. > Full wave loop is the best and quietest on RX. > Vertical plane. > I especially like rectangular with 1/4 wave verts and 3/4 wave horizontals > You should try that 160 loop on 80 with a 1/4 wave open wire feed to get > the impedence down to a reasonably easy to match value. > > If no one is on LF from KH6, I'm relocating there in > May 2002 and can put something up. > > As for marsh. > T2 to East Africa on 75 phone with 35W and good copy > from a biconical cage with 130 radials in a salt marsh in the > middle of the Pacific. Got through on 160CW as well. > > -bob > > ---------- > | From: David Riley > | To: lowfer@qth.net > | Subject: Re: [Lowfer] swamps and such > | Date: Monday, September 25, 2000 1:22 PM > | > | The jury is in and the results are printed in FCC tables in the form of > | ground conductivity curves. > | > | Salt Water is 5000 micromhos per meter conductivity and believe me you > can > | hear best out on the ocean by far. Transmit too. > | > | Jungle and treed area is worse case. > | > | Rule of thumb: > | > | If you are on a salt water marsh like WBZ-AM or in Brant Rock where the > | first radio voice broadcast took place in 1906 then a vertical with > radials > | is for you. One way to beat poor soil is to make the radials 'resonant'. > | This you may do by using insulated wire radials slightly shorter than a > | quarter wave and 'loading' while watching RF current in that leg. > | > | If you are on a rock mountain or useless conductivity soil like sand then > | think about using a loop or balanced antenna. KDKA-AM Pittsburgh uses a > | 'Franklin' which amounts to a center fed half wave up in Allison Park on > the > | rocks. I use full wave loops on 160 and 80 and hav'nt seen a better > | performer in 50 years. ( more quiet on receive too ) > | > | Alas it is true, I=E/R evan at A.C. > | > | 73s de Dave - 1A > | > | * Whats up for this season??? > | > | ----- Original Message ----- > | From: "Pierre Thomson" > | To: > | Sent: Monday, September 25, 2000 8:00 AM > | Subject: [Lowfer] swamps and such > | > | > | > Hi Mike, > | > > | > I used to wonder the same; it seems like AM broadcast stations are > | > | > | To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > | send to list!!) Send on list submissions to lowfer@qth.net > To unsubscribe, send to MAJORDOMO@qth.net "unsubscribe lowfer" (Do not > send to list!!) Send on list submissions to lowfer@qth.net From akestelo at bellatlantic.net Tue Sep 26 15:12:19 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:43:00 2003 Subject: [Lf] [Fwd: LF: Propagation measurements on-line] Message-ID: <39D0E700.9D6F291@bellatlantic.net> Alan Melia wrote: > Hi David, the software I am using at present has no facility for output of > the data whilst it is being collected. Whilst it would be possible to write > something I have other more pressing priorities. I think from the > corresponence that John and I have had and some comments from Dave G3YMC, it > is not really necessary to go to those lengths. > > John monitors DCF39 and another of the DCFs below the band. It is > interesting that often these show slightly different results, which may be > due to the different frequency. If the differences in strength are due to > Optical-type interference then location and frequency do play a part in the > timing of peaks and nulls. As Dave says he gets peaks and nulls at different > times to me, and often higher peaks. Some comments from Laurie confirm the > same story.....the general picture for a night is similar but the > 'fine-structure' differs with location. In general Johns appreciation of > band condition from his knowledge of the variations in the DCFs coincide > quite well with my findings listening to CFH. (Well I think we would > generally expect the path to be reciprocal) The main differences being due > to the higher ERP of the DCFs, and the different frequencies. > > During unsettled periods the signal from CFH can rise to high levels very > quickly (over a matter of a few minutes) In the more stable periods it seems > to rise more slowly but stay up for much longer. I need more plots of the > stable periods with my latest set-up, because the arrangement I was using > earlier was running into saturation at the higher levels, and is not > reliable > > Cheers de Alan G3NYK > Alan.Melia@btinternet.com. From akestelo at bellatlantic.net Tue Sep 26 15:17:04 2000 From: akestelo at bellatlantic.net (Andre' Kesteloot) Date: Thu Jul 3 13:43:00 2003 Subject: [Lf] [Fwd: LF: Masts for LF] Message-ID: <39D0E820.5B8AF14A@bellatlantic.net> john sexton wrote: > Hi All, > We are looking for some advice on guying masts for typical LF verticals with > some top loading wires from those Lowfers with experience. There might be a > small loading coil at the top of the mast. > Tracey Gardner and I and a number of others are about to purchase some 18 > metre masts from Von der Ley in Germany. They are made of fibre glass and in > 6 sections of 3 metres each varying in diameter from 58mm at the base to > 23mm for the top most section. The base of the mast sits in a metal boot > which is bolted to a ground spike. > Guying collars (3 eyes) are available for each of the 4 topmost sections, > i.e from 6 metres up. Would two collars be sufficient, for example for the > top and third down sections? or are more necessary? > They also offer a 6 foot 18mm diam top extension to reach 20 metres. Would > the same guying do, or are more collars necessary? > All advice will be gratefully received. > Tnx John, G4CNN > > _______________________________________________________ > Say Bye to Slow Internet! > http://www.home.com/xinbox/signup.html From riese-k3djc at juno.com Thu Sep 28 17:43:17 2000 From: riese-k3djc at juno.com (Bob RIESE) Date: Thu Jul 3 13:43:00 2003 Subject: [Lf] Fw: Topband: Interesting article on LF antennas and propagation Message-ID: <20000928.180552.-126029.1.riese-k3djc@juno.com> LF ers If you have access to the IEEE journals (perhaps at a technical library), check out the August 2000 issue of the IEEE Antennas and Propagation Magazine where you'll find a fairly technical but tutorial-type article, "Propagation Prediction Techniques and Antenna Modeling (150 to 1705 kHz) for Intelligent Transportation Systems Broadcast Applications". A portion of the abstract reads: "This paper discusses the basic aspects of radio-wave propagation and antenna modeling in the band of frequencies from 150 kHz to 1705 kHz. The paper contains descriptions of both sky-wave and ground-wave propagation-prediction models, in addition to the methodology used to analyze antennas that operate in this band. A method of calculating and normalizing antenna gain for systems computations is also discussed. The sky-wave models described in this paper are valid from 150 kHz to 1705 kHz. The ground-wave models described in this paper are valid from 10 kHz to 30 MHz. The propagation of radio waves in the band of frequencies from 150 to 1705 kHz includes both a ground wave and a sky wave, and is quite different from propagation at any other frequency. The methods used for antenna modeling and analysis in this band are also quite unlike those in other bands..." The upper end of the frequency ranges mentioned is close enough to 160 that it should be of interest to many of us. 73, John W1FV -- FAQ on WWW: http://www.contesting.com/FAQ/topband Submissions: topband@contesting.com Administrative requests: topband-REQUEST@contesting.com Problems: owner-topband@contesting.com