[Collins] KWS-1 that screeches!

[Roger Shultz]

Why these things find me I will never know but the KWS-1 which I am
presently working on actually "screeches"  during tune up (probably out of
some sort of unrecognized pain) .

The sound I hear is coming from the RF PA compartment  near the rear of the
chassis between the 6AL5 ALC rectifier and antenna connector as near I can
tell.

As the PA is driven harder in the operate position the screech increases in
frequency (high pitch) and intensity. The plate current does not seem to be
affected as this occurs. It also makes the sound in the tune position but
not as loudly.

I thought it might be the RF choke L404 under the spaghetti arcing but that
is not it.

This sound is not like "frying" that would be associated with arcing but an
actual "screech" is the best way to describe it. I have been able to
visually observe the RF PA compartment with the top cover off in near
darkness and I can't see any arcing or any other visual clue.

I really need to resolve this because I think it's a symptom of some sort of
malfunction causing the rig to tune erratically at times. All observations
have been done on 80 meters so far.

Has anyone seen this oddity occur and if so what in the world was this
strange problem? Any suggestion is appreciated.

73, Roger, NJ2R