[R-390] Paper Capacitor Replacement II

[Barry]

With all this talk about capacitors, I thought I'd ask about HV polypropylene caps.  What are some of the characteristics to watch out for with this construction?

The reason I ask is I have a General Radio C bridge that lost its standard capacitor (0.5uF at 800V).  I have some polypropylenes from WIMA that I'm considering using to replace it.  Particularly, I have a 0.33, a 0.15, and 0.011 that I planned to put in parallel and then finish with silver micas to get as close to 0.5uF as possible.

Thanks,
Barry - N4BUQ