Paralleling electrolytic capacitors for testing purposes

john w. king jbkking at BELLSOUTH.NET
Wed May 16 07:24:57 EDT 2001

I have an Hammarlund HX 500 that has a raspy note with what seems to be about a 120 cycle note on the carrier and audio. I paralleled a brand new electrolytic with each and every old electrolytic in the transmitter FOR TESTING AND ANALYSIS PURPOSES. The procedure cleaned up the signal almost completely, however; there is still something "not quite perfect" on the carrier. My theory is that the old electrolytics in parallel with the new ones degrade the performance of the new electrolytics and thus there is still a TRACE of 120 cycle hum on the carrier. In your experience, have you found that a bad electrolytic degrades the performance of a new one in parallel with the old???

I have cleaned all cable connections with de oxit and all tube sockets to eliminate any residual hum induced by ground loops or bad grounds due to oxidation.

The transformer has a shorted filament winding or open filament winding and a previous owner replaced the filament winding with a separate filament transformer. The has an audible hum just like a solenoid, which I attribute to the shorted filament winding. otherwist, the transmitter cranks out a solid 110 watts of carrier.

I would appreciate your serious thoughts and ideas regarding the residual hum after paralleling all electrolytic caps with new ones. I will remove and refurbish the old cans. Thanks and 73, John, K5PGW

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