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[aprssig] Homebrew transmitter

Jason Winningham jdw at eng.uah.edu
Tue Aug 29 15:30:12 UTC 2006


On Aug 29, 2006, at 10:06 AM, Stephen Brown Jr wrote:

> I got this crazy idea to build a 100% homebrew tracker for car and I 
> am looking for plans for a xtal controlled transmitter on 144.390 I 
> was planning on coupling this to an opentracker, has anyone ever 
> attempted or done this? I know MFJ makes a xtal controlled data radio, 
> but I didn't want to spend what they are asking on it, and also the 
> ten-tec 2m kits are no longer in production. I have no need for a 
> receiver as this will be xmitting only, anyone have any thoughts?

check the PicoBeacon at www.kd7lmo.net.  He uses an AD9954 DDS (direct 
digital synthesis) chip to directly generate an RF signal, which is 
then amplified to 500mW.  You'd basically have to design the 
transmitter from scratch, using kd7lmo's design as a starting point.  
(You said 100% homebrew. :)

Ramsey occasionally has an SMT xtal transmitter listed, the "Rocket 
Tracker".  I think it's $75 assembled, about $50 kit, and has around 
25mW or so output power.  The crystal will put the unit at or near 
146.565 for T-hunt purposes, so you'd have to get crystals made for 
144.390 to get it on the APRS freq.

-Jason
kg4wsv





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