Where to find high voltage electrolytics

[G7PSK]

Hi, I need to find a source of high voltage electrolytic capacitors that wont cost an arm and a leg.
The one I am looking for at present is 5nF (0.005 micro farads) at 1000 volts non polarized electrolytic. This is on an old radio dating to 1947.

[rsjsouza]

I have been in a similar situation before, and I replaced it with a ceramic or disc cap without apparent problems (it was a 1957 radio). Would that work for you, given that high voltage ceramic caps are easier to find?

[mzzj]

Hi, I need to find a source of high voltage electrolytic capacitors that wont cost an arm and a leg.
The one I am looking for at present is 5nF (0.005 micro farads) at 1000 volts non polarized electrolytic. This is on an old radio dating to 1947.

Electrolytic? Sounds like trouble to find...
Maybe you can replace it with 4.7nF  ceramic or plastic capacitor + series resistor to "crappify" the plastic cap to same level as the orginal.

[Radio Tech]

I mostly replace them with the "orange drop" type caps.  Been doing that for years. Some of these electrolytic caps are impossible to find.

[G7PSK]

Thanks for that. I have now found some 4.7nF polyester caps at 1000 volts DC. Dont know why they chose such a high voltage as the HT voltage is only 120 volts from a battery so for much of the time it is lower than that assuming that the battery voltage dropped during use.

[SeanB]

With a HT of 120V from a B+ battery any cap above 160V will work for supply decoupling. Myself I would increase the value to 100n  250V polyester, unless it is a screen grid, where I would use the original value but rated for 3 times the battery voltage as the screen can be driven to double the supply in a push pull amplifier with output transformer.  You can use a 4n7 630V unit there.

[G7PSK]

With a HT of 120V from a B+ battery any cap above 160V will work for supply decoupling. Myself I would increase the value to 100n  250V polyester, unless it is a screen grid, where I would use the original value but rated for 3 times the battery voltage as the screen can be driven to double the supply in a push pull amplifier with output transformer.  You can use a 4n7 630V unit there.

It is actually across the input to the speaker impedance matching transformer, but all the capacitors are rated at a 1000 volts on this radio, obviously they wanted to make sure the radio would last until some one got around to inventing microchips.