[R-390] Gain drift

[dog]

Interesting. I disconnect TB102, 3-4, ground 4 and 3mV into J513 is way 
too much RF for the carrier meter in AGC mode. Reduce the input to about 
250uV and that gives me 50 on the carrier. 0V on TB102-3. About 5 
minutes later the carrier drops to 0. I have to increase the RF input to 
1.3mV to get 50 on the carrier again. It seems to be holding there, but 
there's 0V on pin 3 no matter what I do. Carrier has been holding steady 
for half hour now with 1.3mV in. Oh, wait the voltmeter is not plugged 
in. Let's start over.

I need to get that other IF module working which means repairing the 2KC 
filter. That will take a few hours if I can fix it. It was working but 
all of a sudden showed a short on one side. Hopefully it's just a wire 
that I can push around, otherwise I need a 2KC filter or do without it.