[R-390] Some thoughts on capacitor leakage

[windy10605@juno.com]

Continuing on with my R-390 project...........
Time to decide which mica caps are to be replaced. Many of them "fail" at
500V in the "mica" cap position on the Heathkit IT-28 cap checker where
the eye closes at roughly 0.1uA for the "paper/mica" cap position and is
a little on the sensitive side (an Eico cap checker I had, closed at
1.5uA). So here is a better way: after determining the voltage settings
on the cap checker are "close", insert a digital uA meter in series with
the leads and read the real leakage at the WV. The C327 mica (Chuck
Rippel says it's a problem capacitor) read 2.5uA �.clearly a bad mica.
Most of the mica capacitors which closed or started to close the eye on
the IT-28, really read 0.1uA or less at 500V ...perfectly good.
73 Kees K5BCQ