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RE: Spec's on caps
Hi Eddie, and all on list,
I would hope your Mica caps can stand quite a high rep-rate.
I am shortly going to be cracking open 3 pulse forming networks that
contain 2x 25nF mica caps each, with tapped inductances, to rebuild into
a big Tesla coil primary cap (they do not contain PCB oils, but good old
mineral oil!)
I'm guessing that mica caps are pretty good pulse caps as the PFN data
sheet quotes 500 pulses/sec in 1 microsecond pulses at 15 kV per cap.
I hope to get a reliable cap built based on these units, possibly x6 to
give 16.6nF at 45kV, or if I can find another couple of PFN's , x9 to
give 25nF at 45kV
I've heard that polypropylene is the best dielectric in town, but very
little about the performance of mica in TC pulse caps.
I guess few coilers come by mica caps very often (they would be VERY
expensive to buy new!) but they must be ok, otherwise why would the
military choose mica for their PFN's in their radars!
Good luck with your recons, I think they will work well, but watch the
voltage ratings.
Like me you will need at least 2 or 3 in series to get a healthy safety
margin.
One of the local TC builders came across a big Dubilier, multi unit,
stacked plate mica cap, at the local military surplus yard.
One of the units had failed, and completely vapourised its connections,
so I dont think there's any doubt about mica's low series resistance and
pulse performance!
Beware though, this cap contained PCB oil!
Cheers, Martin Dale Tesla Coil Builders of
Nottingham
>----------
>From: Tesla List[SMTP:tesla-at-pupman-dot-com]
>Sent: Friday, November 06, 1998 6:26PM
>To: tesla-at-pupman-dot-com
>Subject: Spec's on caps
>
>Original Poster: Eddie Burwell <eburwell-at-HIWAAY-dot-net>
>
>I have some Stanley Recon mica caps model# zp203c503-2 Rated .05uF 20KVPK
>
>Does any one have any info on the pulse rep rate these suckers can withstand?
>
>Any expirences with reconstituted mica caps in general?
>
>Many thanks in advanced,
>Eddie Burwell
>
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