{Collins} KWM-2A problems and tubelore question



Hello to the group.  I have returned to Ham Radio
after an almost 16 year absence and decided to get the
radios I wanted the first time: Collins.  Of course, I
bought them from ebay with the predictable result: one
works pretty good and the other has problems.  

My background, I used to have an Advanced class
license, and I taught electronics in the Air Force, so
I have a fair amount of technical skills.  Plus, I
built several Heathkit rigs and did some homebrewing
back in the day.  I've returned to Ham Radio with an
Extra this time.

My questions;

My KWM-2A has a self oscillation somewhere.  When I
tune Z5, its frequency changes.  Any ideas where to
start?

Next: in section 4.5.1.2 of the instruction book, it
says to disable the screen circuit before proceeding
with the 455-KC IF alignment.  Is this really
necessary, or is it sufficient to simply bias the
finals past cutoff?  I'm guessing that the real
purpose behind removing the screen voltage is to just
prevent overheating the finals while messing with T1
and C54.  What's SOP here?

Finally, I've forgotten most of my "tubelore".  I also
have a KWM-2 which works pretty good.  But, both rigs
have one tube (different on each) that glows blue.  In
one, it's V13.  In the other, it's V3.  Swapping both
out doesn't fix the problem.  Is this a sign of some
voltage or drive problem that I need to address.

Thanks in advance,

Bob, AE6RV
Sponsored by the Collins Collectors Association http://www.collinsradio.org
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