[Collins] KWM-1 Questions

[Dr. Gerald N. Johnson]

On Sat, 2008-06-14 at 10:14 -0500, Gary H. Harmon, Jr wrote:
> Any experts out there? 
> 
> 73, gary
>  
> Gary H. Harmon, Jr. / K5JWK
> 6003 Archwood
> San Antonio, TX 78239-1504 
> 210.884.6926
> gharmon at idworld.net
>  
I have an old schematic and have downloaded the printed manual from the other
association web page and I've looked at one or two in passing. Since
the KWM-1 was designed by the same people who grew up designing the 51J,
the 74A, the 32V, the S-line and who went on to design the KWM-2 (and
the 821A-1 along with lots of smaller broadcast transmitters) the
failures are much the same, starting with the black beauty capacitors,
tubes, resistors, mechanical filters and crystals because the components
are the same and the circuits are quite similar. We know from experience
that the black beauties are leaky, so many and so much its not worth the
time to test them, just replace them. Carbon composition resistors are
known to drift (generally upward in frequency) with time, heat, and
humidity. Some are out of tolerance after 45 years. Some are worse than
out of tolerance if worked hard. Tubes are in sockets because they are a
wear item with a much shorter life than the radio itself. Vacuum tube
radio (TV or industrial equipment) repair has always begun with the
tubes, because they had the highest failure rate in service.

And I'm good at analyzing circuits to see what a failed part might do to
voltmeter readings and radio performance.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer