[Collins] Got that sizzle

[Gerald]

On Mon, 2005-12-05 at 10:49 -0500, pentoad at aol.com wrote:
> After flawless operation for the past six years, my KWM-2A is showing 
> disturbing signs...  When I try to tune, as I get closer to resonance, 
> I start to get a disturbing sizzle (the frying bacon sound) from the 
> transceiver.  The set is rack-mounted, so I really haven't been able to 
> get a feel for the source.  I've checked all connections through the 
> 30L-1, 312B-4, and out to the antenna...everything's right.  
> Suggestions on places to focus my troubleshooting as I pull the 
> transceiver out of the rack will be welcome.
> Thanks and 73,
> Ed N0AUB

I'd look for dust in the PA plate compartment. On the tubes, the plate
RF choke, the PA tuning capacitor, and the PA coil. Check the
compression mica loading trimmers for failed insulation, try different
bands. Check the bandswitch contacts and the bandswitch insulation.
Cleanliness often cures such sizzles.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer