[aprssig] HF APRS Transceiver

[Stephen H. Smith]

Rich Garcia wrote:
>
> I ran a HFGate for over 8 years on a Kenwood TS-850S/AT 24/7 365 and after 2
> trips to the repair station and the APRS-IS going on line I gave up. That
> was/is a great rig and should not be wasted on one specific frequency
> getting very little use.
>
> Rich
> K4GPS
>
>   


I've been running a Kenwood TS-50 on 30M HF APRS for about three years 
now 24/7.  Ideal for this application:  small, low power consumption on 
RX and (in a living room constant temp environment) stable enough. 


One potential low-cost candidate for fixed-frequency APRS applications 
on HF is the "Small Wonder PSK31" transceiver.  These are essentially 
single-band (40M, 30M, 20M) fixed-frequency (crystal-controlled) SSB 
transceivers with a wider-than-average passband. They are intended for 
PSK31 operation where all tuning is normally done at audio using a sound 
card program with a waterfall panoramic display.  


You could just as well connect a packet TNC, TinyTrack/OpenTrack or 
soundcard interface and AGWpe to one of these radios.  The only change 
is that you would have to replace the channel crystal with one that 
places the radio on the APRS channel in the band instead of XX.070 MHz, 
where they sit for PSK.   The kits for these single band radios are 
about $100 for a 3-4 watt PEP output  transceiver. Note that for normal 
constant-carrier X25 FSK packet used by APRS, you could drive the TX to 
saturated key-down max power out. (i.e. you don't have to reduce the TX 
out to minimize distortion as you would with PSK31).   The TX power 
output may be a bit low, especially for a mobile, but for monitoring 
they might be ideal due to the extremely low RX power consumption.  And 
of course you could scrounge up an old CB "footwarmer" at a swapmeet to 
get one of these up to 50-100W out.   

I have been considering one of these for my 30M APRS receive system to 
replace the TS-50.    Details at:


      http://www.smallwonderlabs.com/  




--

Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      14400    [Think bottom of the 2M band]
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