I described my difficulties in getting the 38S running over the weekend, and
thanks to those list members who were kind enough to respond with some
preliminary ideas. Unfortunately, I'm not much further along, perhaps because
I didn't describe the problem well enough.
Here's another plea for assistance!
Symptoms:
* No receive
* Squeal (like a sweep generator) audible in headphones when I kill the
power
38S, stock version
Transmit seems to function OK (uncalibrated range 10.105 - 10.122), power out
through WM-1 wattmeter just < 300 mW.
I'm beginning to suspect U5: with the screwdriver test, I get a loud tone on
Pin 6 (input to first op amp) but no tone on Pin 7 (output from first op amp)
or any successive pins throught the receive chain. Nowhere on the chain do I
hear any AM radio stations as many others have reported using the screwdriver
test.
However, Ori's debugging tip sheet says, "You should hear the sidetone with
key down. This tells us that the audio amp circuit (U5) is functioning." And
for key down, I *do* hear the sidetone loud and clear.
I've performed continuity checks from pin to pin throughout the receive chain
with an ohmmeter and have verified electrical connections. I've verified
polarity of all component insertion. Further, all the voltages on U5 per Paul
Harden's sheet match perfectly.
So is my U5 bad? Before I go to the trouble of replacing it (oh well, it's
soldered and not socketed), is there something else I should check or be
aware of?
Thanks for any suggestions.
72 and hope to CUL on 30m
Paul, AA1MI
QRP-L #360
PGSPersEng@aol.com
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