[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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