Subject: 4000PF caps
From: richard.quick-at-slug-dot-org (Richard Quick)
Date: Sun, 24 Sep 1995 06:15:00 GMT
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Quoting mark.graalman-at-mediccom.norden1-dot-com (Mark Graalman):
> Hi Richard,
> I thought I'd drop you a note to pass on if you want. The 4000
> PF 30 KV caps that are advertised in with the TCBA newsletter
> are not 4000 pf (.004 ufd) I bought some awhile back, and they
> are good caps but the measured value is really .0024 ufd NOT
> .004 they are mismarked. Other than that, they work well.
Right, I bought a few of these also. This particular batch
originated, I believe, from: Hi-Way Company, Surplus Electronics,
305 Wisconsin Ave., Oceanside, CA 92054 Tel: 619/967-7225
Hi-Way had about 1000 pcs in stock which were bought by George
Trinkaus. George is now retailing these capacitors through
HIGH VOLTAGE PRESS, 4326 SE WOODSTOCK, #489, PORTLAND, OR 97206
USA, Tel: 503-775-3209
The price is $15.00 (usd) per unit. These are Barium titanate
"doorknobs" with a 30 KVDC rating that are used as filter caps in
radar sets and high power transmitters. The actual capacitance of
these units are 3000 pf (.003 microfarads) with a +/- 10%
variance. Figure they are going to be lower, not higher.
These caps are not pulse rated, and the dielectric has a very
high RF dissipation factor. When used as pulse capacitors in the
Tesla tank circuit they get pretty hot and have a finite life
span with 9 KVAC (rms) inputs. The secondary spark on coils using
these caps in the tank circuit tends to be thin, spindly, and
These are excellent RF bypass capacitors to protect the step-up
transformer, indeed, this is their designed application.
... If all else fails... Throw another megavolt across it!
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