[OZAPRS] Homebrew HF APRS transmitter

[Steve]

I heard you at around 10:00 this morning. Only one packet so far though.

What a great idea in pushing a PSK31 kit into use for HF APRS. Not 
enough of this sort of thing going on I reckon!

Steve (VK2ZSZ-4 RX only HF I-Gate, "netted" with WWVH only - oops, 
shouldn't start that one up again! ;-).


On 07/06/2011 09:50 AM, Peter Schrader wrote:
> A few have asked what I put together.
>
> I built a Small Wonder Labs PSK31-30 kit, changed the main LO crystal 
> to suit the 10147.6 kHz dial frequency, with a 4MHz IF, the LO becomes 
> 6147.6 kHz.  The crystal came from Hy-Q in Melbourne.  Unfortunately 
> Small Wonder Labs have discontinued production of these kits, 
> http://www.smallwonderlabs.com/.
>
> Used a Communications Concepts 20W driver amp module for the PA, setup 
> a pi attenuator to drop the PSK31 RF output power to 100mW to suit the 
> PA input.   http://www.communication-concepts.com/an779L.htm
>
> An Argent Data Opentracker2 does the encoding, I had all sorts of 
> trouble using a OT1+, it is much more susceptible to conducted RF.  I 
> did try all sorts of techniques to stop the RF travelling up the 
> control wires, ending up giving up and using the OT2.  Using the ADM1 
> GPS from Argent Data.
>
> I constructed a standard LPF from Amidon cores and silver mica 
> capacitors to keep the output clean.
>
> All packaged in a metal instrument box I bought from Jaycar.  I 
> installed a set of powerpoles under the dash which are energised once 
> the engine is running.  The box sits under the drivers seat.
>
> Antenna is a surplus tapped helical whip to which I hard wired a 
> wander lead to make it resonant on 10147 kHz, it sits on the bull bar 
> on a heavy duty Codan spring base.
>
> I guess it would have been easier to use something like a Codan, but 
> would have not been not as much fun :-)
>
> 73,
> Peter
> VK4EA
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