Re: Fw: Fair Radio Sales HV capacitor

To: tesla-at-pupman-dot-com
Subject: Re: Fw: Fair Radio Sales HV capacitor
From: Bert Hickman <bert.hickman-at-aquila-dot-com> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Fri, 25 Dec 1998 20:12:40 -0700
Approved: twf-at-verinet-dot-com

Tesla List wrote:
> 
> Original Poster: ESchulz531-at-aol-dot-com
> 
> Hi,
>         I have two of those capacitors.  They work great.  I get 37"
>  to a ground rod with 15kv 60ma at 120bps.  6" secondary 20
> gawg. 3/8" copper tubing primary with RQG and one cap.
> 
> Running at 12kv 250ma they start to get warm and I let them
> cool after 10 minutes of run time.  I have had mine for 2 years
> and they haven't failed.
> 
> Sometime this Christmas I am going to run them at higher
> voltages.  If all goes well or they die I will report it to the list.
> 
> Erik Schulz
> 
> >   I ran across a HV cap advertised in Fair Radio's latest catalog page 32,
> >   0.01 mfd at 100KV, wonder if anyone had had any experience with them in
> >   Tesla service?  They've lowered the price to $87.50.  I imagine it could
> >   work in, say, a 15kV/30 or 60 mA neon transformer type coil.  Sure beats
> >   the mess of "rolling yer own" and probably less money in the bargain.
> >
> >   What's the consensus?
> >
> >   Stephen, KJ6LH

Stephen and all,

There's good news and bad news with these caps. These are
Mylar-dielecric DC-rated caps, and they WILL heat up under Tesla Coil
use. As long as you keep run-times relatively short, and allow
internally generated heat within the capacitor rolls to distribute
before overheating occurs, they will work. Spark output will not be as
"hot" as with polypropylene or polyethylene caps, and the caps cannot be
operated for extended periods without risking melting & punch-through of
the dielectric. But... they are relatively inexpensive alternatives to
true pulse caps, and they will save you the time and effort of rolling
your own. 

-- Bert --