[OZAPRS] Home brew HF APRS transmitter - follow up

Peter Schrader lists at rumpleteazer.net
Tue Aug 2 16:32:07 EST 2011

Hi all,

A follow up from my earlier posts re a home brewed HF APRS transmitter.  
The CCI based driver amp sacrified itself over the weekend, most likely 
because I had the corner pegging set a bit to quickly in the Tracker2.  
End result was a buggered final transistor and a few open circuit 

Having only a few days before I head off into the bush, I stripped a 
Codan 8525A, leaving the front panel and PA.  I mounted the PSK31 based 
transmitter in the empty space, wired it up the very ruggedly built 
Codan PA, hardwired the LPF to the correct range, gave it 12V and 
voila.  I now have a 100W APRS transmitter.  Sits nicely under the 
drivers seat.

I have backed off the smart beaconing so that beacons go out at 2 min 
intervals at 100km/h, 30mins when stationary, and set the beacons to 
compressed.  Hopefully I won't be hogging the frequency so much now   
The Tracker2 has a nice feature to not transmit under a configured 
voltage.  I've set mine to not transmit until the voltage gets to 13.2V, 
which should be only when the engine is running and charging the 
auxillary battery.

Got some pretty good results on the short drive to work today, proof in 
the pudding will be my trip to the Flinder's Ranges and Lake Eyre 
starting next week.

If anybody wants any details, feel free to shoot me a note.


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