Got in the first 10 Midland XTR memory expansion wafers. 6mgroopannouncment. Conversion article project.

Paul Rinaldo prinaldo at
Fri Dec 28 07:33:57 CST 2007


Meteor scatter (burst) propagation depends on a number of factors that affect the duration of the burst over that specific path. Imagine for the sake of an example that the path is open only for 150 ms. That could mean that the entire exchange needs to be completed during that time. By exchange, I mean at least the transmission of a packet and the ACK.

The critical thing is minimizing turnaround time. Once a path is available, it typically can support very high speed data, even at video bandwidths albeit for an instant. For 6 m, Part 97 permits a speed of 19.6 kilobauds or 20 kHz bandwidth. An STA would be needed for higher speeds/bandwidths.

A good source of information is "Meteor Burst Communications," by Jacob Z.Schanker, W2STM. I have the book and a set of disks unfortunately of the 5.25-inch persuasion and I no longer have such a drive. I'll bring them to tacos on Saturday and we can arrange a format conversion.

Another source of information is the work by Joe Taylor, W1JT, such as at


-----Original Message-----
>From: Terry Fox <wb4jfi at>
>Sent: Dec 28, 2007 3:10 AM
>To: Glenn Baumgartner <gbaumgartner2 at>, "Tom Azlin, N4ZPT" <n4zpt at>, Michael Chisena <ka2zev at>
>Cc: tacos AMRAD <tacos at>, Evan Alford <ear_ltd_ at>
>Subject: Re: Got in the first 10 Midland XTR memory expansion wafers.	6mgroopannouncment. Conversion article project.
>My guess is that 1200 baud packet is toooooo slow.  From what I remember
>about meteor work, it lasts a very short time.  Just syncing the modems may
>take too long (unless you do much faster than the old Bell 202 style modems.
>I think you will need a much faster modem, and probably a higher data rate.
>But, I could be wrong.
>----- Original Message ----- 
>From: "Glenn Baumgartner" <gbaumgartner2 at>
>To: "Tom Azlin, N4ZPT" <n4zpt at>; "Michael Chisena" <ka2zev at>
>Cc: "tacos AMRAD" <tacos at>; "Evan Alford" <ear_ltd_ at>
>Sent: Thursday, December 27, 2007 9:37 PM
>Subject: Re: Got in the first 10 Midland XTR memory expansion wafers.
>6mgroopannouncment. Conversion article project.
>> Ok gents we are well on our way to having numerous 6 m radios with voice
>> capability lots of power and a ground wave range in the tens of miles at a
>> minimum most of the time.  Work I have read about in the past indicates
>> purpose built meteor networks (SnowTel and Alascom)  got out to 100-150
>> miles all the time just on ground wave and forward scatter, meteors only
>> came in to play after about 400 miles and out to about 1200 miles as I
>> remember, but FAST was always the key to keeping up a link and making a
>> system profitable.   Personally I think the digital operation of our
>> is the way to go.  Voice of course should not be prevented or eliminated
>> Meteor Scatter I would bet is the way to plan going if some new USEFUL 6
>> meter technique or service is to evolve.  Anyone want to hazard a guess
>> "BEST" (read, cheapest, easiest, most universal, quickest)  way to do it?
>> 1200 baud packet?  AFSK?    HSCW...(high speed CW) which with an FM radio
>> might really only be Audio keying of the radio driven by a sound card I
>> suppose.  True CW would be a bit difficult with an FM radio but not
>> impossible if you really wanted to nearly rebuild the radios.  For the
>> moment it seems that the traditional  "2 meter" style FM 1200 baud packet
>> looks best to me.  Any one want to argue? (or propose a better way)  We
>> an approach to try experimenting with for starters and have a next effort
>> plan if the first doesn't work out so well in the foreseeable future.
>> little to no experience with packet at the moment and I have some doubts
>> about the protocol and whether it can handle small and or many fragmented
>> packets.  Seems to me if the packets were quite small that if anything got
>> thru on a given meteor trail then a whole (small) packet would.
>> Multiple small packets sooner or later make a message no matter the time
>> assemble them.  What does anyone think about "fast" PSK 31, ie MT 63?   or
>> faster?  Just a little chum for AMRAD's sharks to feed on for now.  GAME
>> guys!  Lets start thinking, building, experimenting we've been a bit dull
>> a radio club for some time now. 73 ..KA0ESA.
>> ----- Original Message ----- 
>> From: "Tom Azlin, N4ZPT" <n4zpt at>
>> To: "Michael Chisena" <ka2zev at>
>> Cc: "tacos AMRAD" <tacos at>; "Evan Alford" <ear_ltd_ at>
>> Sent: Wednesday, December 26, 2007 8:58 PM
>> Subject: Re: Got in the first 10 Midland XTR memory expansion wafers. 6m
>> groopannouncment. Conversion article project.
>> > Hi Mike,
>> >
>> > Not sure about others but I will not be able to make a Tuesday night
>> > net.  That is the Fairfax ARES meeting night, the VWS board meeting
>> > night and the Vienna Wireless HF digital net night. the previous
>> > activity night was on Wednesdays at 7PM or so.
>> >
>> > I am interested in the upgrade to the 6m radio.
>> >
>> > 73, Tom n4zpt
>> >
>> > Michael Chisena wrote:
>> >> All, Got the first ten units of the plug in module that expands the
>> >> Midland 70-0375C (and similar xtr) from 22 to 99 channels.   I hope to
>> >> get a little time to edit my 99 channel list, and print up some copies.
>> >>   Here is what I'm thinking.   If you have one of these radios, bring
>> >> to Taco's Saturday.  I can drop the wafer in during lunch. Four screws,
>> >> one snap on housing, that's the mechanical side.   If I bring a gell
>> >> cell battery, cable and control head, I might be able to re flash the
>> >> new program at the table, if not, then in the car.
>> >> ..................... !   Give this a look at.
>> >> Feel free to join in and make
>> >> comments.   Looking to start the 6m net on Tuesday nights around 20:00.
>> >> The first few are Tuesday Jan 8Th, 15Th The third Tuesday is the 22ND,
>> >> that's the dinner meeting at Old Dominion Brewing in Ashburn.
>> >> .................................................. Been casually
>> >> on an article on how to convert these radios. This is some of what I
>> >> have so far. Comments welcome.     Ive been reprogramming the TVI
>> >> aka Low Pass on the XTR edition of that radio 70-0375C and have been
>> >> getting flat 110 watts from 50 to 53MHz.   Also look at my flickr page
>> >>   it
>> >> is by no means complete so treat this like a work in progress.   Keep
>> >> safe Mike
>> >>
>> >> "You are, what you do, when it counts"
>> >> The Masso
>> >>
>> >> "Gravity, the quickest way down"
>> >> Mayor John Almafi
>> >>
>> >> "You ever drop an egg, and on the floor you see it break?
>> >>
>> >> You go and get a mop so you can clean up your mistake.
>> >>
>> >> But did you ever stop to ponder why we know it's true?
>> >>
>> >> If you drop a broken egg you will not get an egg that's new?"
>> >>
>> >> MC Hawking
>> >>
>> >>
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