My 38s was getting low output following momentary
power application *before* cutting the appropriate
trace on the PCB. I replaced the final (IRF-510
which had gotten warm) and the 74HC240 (socketed).
Other than low output, signal had been great, but I
now got a few complaints of "drift." I started listening
very carefully. Receiver didn't drift, but the transmit
frequency did change very slightly during operation as
monitored on my FT-990DC.
Only things changed were the 74HC240 and final, so
what the heck, and by gosh and by golly, it was the
74HC240. No more drift (except the operator).
The replacement that caused trouble was: HD74HC240P
Seems it was the TX offset, but why? I don't know.
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