[Lowfer] WD2XKO WSPR-15

[Dexter McIntyre W4DEX]

One more sequence from the drifter then QRT.  Storm line is getting 
close and winds already gusting to 30+ mph.

I've spent way to much time trying to reduce the drift in the old 
FT817.  I really don't need to be improve it for what I mainly use the 
rig for.  It's just one of those problems that isn't necessary to fix 
that turns into a time consuming challenge.  I've tried running the rig 
with a fan blowing on it, running it with the cover off, with and 
without fan, and trying to insulate the tiny plug in reference 
oscillator board from the chassis heat plus some I've likely forgot 
about. But what has come as close to stabilizing it at much as anything 
else was applying a hint from Mike, WA3TTS.  He informed me that the rig 
has an internal voltage regulator that reduces the input to 9.6 volts.  
I assume it was designed to work on that low of voltage because of it is 
capable of operating from an internal 12 volt battery pack.  With 13.8 
volts from a 25 amp Astron there was more heat being dissipated from the 
voltage regulator than from the radio being in transmit mode.  I put the 
covers back on the radio and added 6 power diodes in line with the 13.8 
volts then measured 9.4 volts at the radio.  It seems to work well at 
that voltage and the WSPR-15 drift is alternating between 1 and 2 Hz per 
15 minute sequence.  Not bad for a $75 radio with bad final FETs and no 
TCXO. 

Dex