Worst case is that the crack will continue due to thermocycling or you could
have a partial
vacuum, apparently already up to atmosphere, which could reduce the break down
voltage
to a few hundred volts or less.
73
Bill wa4lav
________________________________________
From: Amps [amps-bounces@contesting.com] on behalf of Ian White
[gm3sek@ifwtech.co.uk]
Sent: Saturday, April 27, 2013 4:43 AM
To: amps@contesting.com
Subject: [Amps] Non-vacuum capacitor
Preparing for an SK sale, I found a 2000pF vacuum capacitor rated at 8kV
which has a small star crack going through the glass, so it isn't a
vacuum cap any more.
However, on the hi-pot tester it is still good to 3kV DC. Applying the
usual factor of 0.707 for peak voltage, and then downrating by a further
factor of 2(??) to allow for the difference between RF and DC, it seems
like this capacitor should still be able to handle about 1kV RMS at RF.
In spite of the air leak, I'm thinking it should be OK to offer it for
sale as a pi-network output capacitor suitable for any amateur power
level.
Anything wrong with that reasoning?
73 from Ian GM3SEK
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