[PropNET-Online] Re: Experimenter hf net organizing

David A Aitcheson - KB3EFS kb3efs at gisco.net
Thu Aug 24 14:21:35 CDT 2006


You bring up some very interesting points that have my curiosity.

John Barrett wrote:
> I've been looking into what it would take to do a DIRT cheap single band 
> SSB tranciever kit based on SDR techniques -- reciever would be simple 
> enough -- analog devices frequency synthesizer or some other clock 
> source at 4X the recieve freq, x/4 counter/decoder and quadrature mux, 
> bandpass input preselect filter, and an 8 stage phase difference filter 
> (resistor/capcitor array) to demod the SSB from the quadrature output of 
> the multiplexer...


> I've read that the reverse will do for transmit also feed audio to the 
> phase filter in reverese and feed the filter outputs to the mux in 
> reverse -- makes for a great deal of shared use in the circuits -- just 
> need some switching to get the audio in and the mux output to the PA

Interesting, I (re?)learned something today.

> I havent got it all in schematic form yet -- pretty much all discreet 
> components except the synthesizer (surface mount) unless you decide to 
> use some other easily adjustable clock source. (maybe add a simple 
> frequency counter and display if the clock source isnt digitally 
 > controlled)

Could this be done with "modules" like a plug in option for the
http://hpsdr.org/ project that Kevin Inscoe has mentioned on tacos in the

If others have a platform that we could create a plug-n-play module for
would that make for easier developement and lower the costs?

> I would MUCH prefer something less than $300 a pop -- for the cost of 2 
> of those RX-320s, I can get an FT100 or FT857 .. all bands, all modes, 
> xmit and recieve... just cant see investing that much in a reciever for 
> propogation studies when there are plenty of much cheaper home brew 
> designs out there that can do the job with cheaper components.

I am liking this; and it sounds like the "The First Domestic Bank of
XYL-ville" would as well! (GRIN)

> As far as a licensed person on staff -- if the school doesnt have one, 
> find a local ham interested in the project and have them setup the 
> station and run it under their call sign.

Not so easy in these post 9/11 days.  If the "State" hasn't most School
Districts have instituted policies that prohibit (at times draconian-ly)
any "non-staff" participation in schools.  In some places parents can
not even step foot on school grounds I am told.  The days of helping out
and community involvement in education are over I am afraid.  Even with
passing a background check one is not guaranteed access to a local
educational facility.

Dave Aitcheson - KB3EFS

> ----- Original Message -----
> *From:* David A Aitcheson - KB3EFS <mailto:kb3efs at gisco.net>
> *To:* tacos at amrad.org <mailto:tacos at amrad.org> ;
> PropNET-Online at yahoogroups.com <mailto:PropNET-Online at yahoogroups.com>
> *Sent:* Wednesday, August 23, 2006 11:54 PM
> *Subject:* [PropNET-Online] Re: Experimenter hf net organizing
> Frank,
> Has any consideration been given to doing a kit for this antenna
> project?
> On first glance this antenna would be the "ideal standard" for a station
> that is going to be set up as a lurker. Say a _RX only_ 10m or 20m
> station that is being run my a SWL or a Technician licensed ham; or for
> that matter a school that does not have a licensed ham on staff but the
> teacher wants to promote ham radio.
> My thinking is... a standard antenna, and a standard receiver (RX-320)
> should equal a standard system that would yield repeatable and results
> from any one signal source. Thus given: station A received at 1, 2, 3,
> 4, etc. would only vary due to propagation differences caused by
> ionospheric changes. The same should be measurable in cases of B, C, D,
> etc. transmitting to 1, 2, 3, 4, etc.
> If the transmitters are all of the same make/model and set to the same
> power levels and feeding as nearly identical antennas as possible with
> the controlling being done by (maybe networked) PIC controllers; then
> true scientific studies can really begin I think.
> Have I interpreted correctly your plans. Thoughts?
> 73
> Dave - KB3EFS(/2) Tech. [FN24bi]
> Web Master http://www.propnet.org <http://www.propnet.org>
> Frank Gentges wrote:
>  > Terry and all,
>  >
>  > Terry Fox wrote:
>  >
>  > > For a first step for receive-only stations, I could probably get an
>  > > RX-320 or PCR-1000 receiver running with an active antenna (Frank's
>  > > e-field probe) fairly quickly. I could use that for both our work
>  > > here, plus the propnet - timehare the radio via the computer.
>  > >
>  > > Frank, maybe we should look at standardizing a receive package
>  > > with an RX-320, active antenna (antenna tuning driven via computer 
 >  > > and cheap A/D converter), plus some sort of cheap computer as we
 >  > > have been talking about.
>  > > Would the LF active antenna up to 10 meters? I don't remember the 
 >  > > specs, and a lot of books, magazines, etc are still packed up
 >  > > somewhere (garage).
>  > >
>  >
>  >
>  > First, the RX-320 should do well at HF without the AMRAD LF
>  > modification. Thus, use it right out of the box.
>  >
>  > Second, the AMRAD Active antenna can be built with the J310 JFET
>  > instead of the high performance CP-666 JFET. For most users that 
 >  > should do the job. You can use the PC board kit and a J310 without
 >  > the complexity of the heat sink. For the HF use. a whip longer than
 >  > the one meter would be a real help. We would keep the PVC pipe
 >  > fittings and use 12 volts DC for power. The transformer could be
 >  > the same or a substitute. We were fighting interwinding capacitance
 >  > to keep power line noise coupling down for LF use. It is not so much
 >  > a problem at HF and everything gets simpler.
>  >
>  > Once I get some time (September perhaps?) I can build up a "standard
>  > package" for our HF work and write it up in the newsletter so everyone 
 >  > can duplicate it easily. This is not that hard or time consuming.
>  >
>  > Then everyone else can concentrate on the other parts of the
>  > problem and propnet.
>  >
>  > Perhaps a SoftRock receiver variant can be worked in here
>  > someplace down the line.
>  >
>  > For a refresher on the antenna go to the AMRAD web page on it at
>  >
>  > http://www.amrad.org/projects/lf/actant/index.htm
>  >
>  > A link to the original article is provided along with many later
>  > notes on the construction.
>  >
>  > Frank

More information about the Tacos mailing list