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1-3 of 3 messages
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Page 1 of 1
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RE: Plans for a simple 2M fox...
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Reply
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by WB6BYU on October 1, 2008
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Mail this to a friend!
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What do you want it to do?
Generally I use an old HT and plug some sort of controller
into the mic jac to provide some sort of audio and an ID
to keep it legal. I've got a number of IC-2ATs around
for this purpose, and often pick them up for $25 at the
hamfests.
I use the "Montreal Controller" since I use a set of
synchronized transmitters for ARDF, but for simple
applications it doesn't have to be that complicated. One
box just sent my callsign repeatedly in Morse code that
I had entered into a 128 bit shift register. I've seen
a couple controllers built using voice recorder chips and
that would be my recommendation: I'd spit the memory into
two parts, half for sending some sort of repeated audio
clip (rooster crowing, telephone ringing, etc.) and the
other half for a voice ID.
For something smaller, there are a lot of microprocessor
crystals around that multiply to 147.456 MHz. A canned
oscillator at 16.384 MHz with a tuned circuit to
extract the 9th harmonic will give you a signal source,
or you can build a 9th overtone oscillator using a crystal
on the same frequency. 18.432 or 8.192 MHz also multiply
to the same frequency, and can be used in an old rock
bound HT that takes crystals in that range.
There are a number of newer designs using the ICS525
oscillator chip: it takes a crystal somewhere in the
HF range and some divider programming to generate signals
in the 2m band. Linear Technologies makes the LTC6905CS5
series Resistor Programmable Oscillator chips that go
up to 170 MHz. A couple different companies offer Field
Programmable Oscillators that you can order for a specified
frequency for less than $10: many of these don't go
quite up to 2m, but you can run them at 1/3 the frequency
and extract the 2m signal from the output. Many of the
older CB crystals were of the overtone type, and when
operated on their overtone frequency near 9 MHz would
put a harmonic into the 2m band.
Here are some links that may give you some ideas:
http://www.homingin.com/joek0ov/mfcupdate.html
http://www.byonics.com/
http://www.west.net/~marvin/microhnt.htm
http://home.att.net/~jleggio/projects/rdf/rdf.htm
http://www.qsl.net/ve2emm/pic-projects/mt525fox/mfx525-e.html
http://www.silcom.com/~pelican2/PicoDopp/MICROHUNT.htm#SQBX
and, if that doesn't keep you busy long enough, start
on some of this list:
http://www.homingin.com/links.html
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