Re: Ceramite caps, was Re: Marx Generator Capacitors

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 04:44 PM 3/12/2003 -0700, you wrote:
>Original poster: "Sean Taylor by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><seantaylor-at-attbi-dot-com>
>
>I have 10 of these red cera-mite caps, and I have no idea if they are good
>for TC duty - any one have any idea? The part number on them is 715C, then
>they have 8422 below that.  They're rated 1300pF, and 15 KVDC.  I was
>thinking about parallelling them all for a cap for a 9/30 NST.  Would these
>work ok? Thanks,
>Sean Taylor

The Ceramite catalog (with datasheets) is available online...They are part 
of Vishay (a huge component company) now.
 From FaradNet: http://www.faradnet-dot-com/catalog/company/ceramite.htm

the 8422 is the mfr date code, 1984, 22nd week.

715C is the kind of capacitor.  There's two kinds, the 715C-DK and the 715C-KT
The DK series is 1.2% diss at 1kHz and the KT is 0.2% at 1kHz.. (DK = 
Doorknob? back from the old Sprague days?)

In my really fuzzy recollection, these aren't particularly low loss, so 
internal heating will be an issue (changing of the tune frequency, 
potential damage)... on the other hand, you've got a bunch, so if you toast 
one or two, oh well....

You could try paralleling 5 of them for 6.5 nF total...

Uh, a 9kV NST puts out 1.4*9kV peak = 12.6 kV.. that's a bit close to 15 kV 
DC..

As a practical matter, I have 3 of this general type (2700 pF,40kV for 8.4 
nF) in a 15/30 powered coil and they seem to have survived.  The 
performance is ok (18" or so sparks to a grounded rod), although nowhere 
near the maximum possible from a 450 VA transformer. On the other hand, 
I've hardly optimized it other than getting it to tune up the first time.