Re: doorknob capacitor

Tesla List wrote:
> >From major-at-vicksburg-dot-comTue Aug 27 22:57:34 1996
> Date: Tue, 27 Aug 1996 19:26:23 -0500
> From: RODERICK MAXWELL <major-at-vicksburg-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: doorknob capacitor
> I have a sprague 30 KVDC capacitor at 4700 picofarads. I don't want to
> use it in the tank circuit but I wonder if it would hold up as a bypass
> cap?
>   Could any of you brave souls help me out?


Doorknobs, like neon sign transformers, are doomed in Tesla service!!!

The bypass service is kinder too them, but the value of yours is a bit 
high!  100pf might be better.  The RF slowly eats out a ring of silver 
around the terminal and the terminal no longer is in contact with the 
silver plate inside.  Thus, as the caps are used, their value drops as 
more and more silver is vaporized and less and less active area of the 
plates remains.  I've cut these open and seen this with my own eyes and 
know this as a fact!

Richard Hull, TCBOR