[R-390] C603 and C606

David C. Hallam dhallam at rapidsys.com
Sat Mar 21 08:12:55 EDT 2009


To relate an experience I just went through with electrolytic 
capacitors.  My Johnson Invader 2000 would not work in the SSB mode and 
had only about 50W output in the CW mode on 80/20M only.  After some 
investigation, I found the LV supply in the exciter section was running 
about 240V instead of its normal 330V.  The cause was the dual 40/40uF 
450V FP electrolytic in the filter.

Testing this capacitor with my old Solar capacitor tester, it showed 
only about .1mA leakage leading me to believe it was OK.  But upon 
checking its capacitance, I got no reading.  I guess it was acting as a 
big resistor but not leaking any current to ground.

I happened to have a new 60/40uF 475V capacitor made by DH Distributors 
in Wichita that was to be used in an HT-37 restoration and used it for 
the replacement.  DH makes FP type electrolytics by putting 
electrolytics inside chrome plated brass plumbing tubing with the proper 
base and a snap plug on the top.  I don't know if they make any plug in 
types.

David
KC2JD/4




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