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Ralph Mowery Ralph Mowery is offline
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Default replacement cpacitors

In article ,
says...

a lot of ceramic caps suffer severe loss of capacity once a few volts are applied. If it works fine, great. If the limited amount of original bass has vanished, that might be why. If rf drifts all over the place as mains voltage varies...

It depends on the type of ceramic, some don't suffer this but most do.


NT


it also can cause nonlinear distortion if C is changing as signal voltage changes.

The other cap type to be a bit cautious of in valve kit is polystyrene, the dielectric has low melting point.

The issues with electrolytics & paper are relatively well known.

Oh, also beware of reduced voltage rails that go very high during warm-up. Caps there might need 400v+ rating despite running at 20v.




Thanks, I may replace the 'replaced' capacitors with some of the 'Orange
Drop' ones I have if I ever pull the receiver back out of the case.

I am using it a boat anchor station from around the time I was born
along with a Johnson Viking ll transmitter. By the time I was old
enough to get into electronics much had switched to solid state, but I
did learn enough to do repair work but replace like parts with like
parts except the paper capacitors with the newer tublar type. As
mentioned electrolytics do tend to dry out after 50 years.