The oscillation might be coming from one of the transmitter stages. Make sure
the final stage is not self-oscillating! My FT-101 self-oscillated once during
a reneutralization attempt - it produced a loud "farting" noise when it was on
the 10M band, followed quickly by the smell of hot (but fortunately not
burned-out) circuitry. Self oscillation is more likely to occur on higher
bands and with the "twitchy" 6JS6C-based finals of the 101. I think later
models switched to different tubes.
Also, reciever oscillations can be caused by the extra resistance and
capacitance of cold solder connections or bad components - an old heathkit
receiver I have oscillated like crazy until I hunted down the cold solder
connections. Once resoldered, it worked fine.
-Wiley KF6IIU
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