[Collins] 32S-3 self oscilation and tuning problems

[Glen Zook]

The 75A-1 does not use the "black beauty" paper capacitors like the 75A-4 nor the "brown beauty" paper capacitors like the 75A-2 and 75A-3.  It uses oil filled "bathtub" capacitors that are mounted on the chassis.  These "bathtub" capacitors are a lot more stable than the paper capacitors.  As to whether or not they should be replaced is "catch as catch can".  In many 75A-1 receivers they are all fine yet in other 75A-1 receivers they are problematic and should be replaced.

Generally most persons who replace the "bathtub" capacitors leave the old ones mounted on the chassis because if they are removed there are several large holes in the chassis.  New "orange drops" or similar capacitors are then wired in placed under the chassis.

Glen, K9STH

Website:  http://k9sth.com


--- On Fri, 10/24/08, Dr. Gerald N. Johnson <geraldj at storm.weather.net> wrote:

From: Dr. Gerald N. Johnson <geraldj at storm.weather.net>

The A-1 will need all the black beauty oil paper capacitors replaced as well as all the electrolytics and probably some fraction of the tubes and ceramic trimmers.