Re: Secondary additions and corona breakout

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Secondary additions and corona breakout
From: Tesla List <tesla-at-stic-dot-net>
Date: Sun, 18 May 1997 23:31:20 -0500
Approved: tesla-at-stic-dot-net

Subject:      Re: Secondary additions and corona breakout
       Date:  Mon, 19 May 1997 09:11:52 +1200
       From:  "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Organization: Wellington Polytechnic, NZ
         To:  tesla-at-pupman-dot-com

Hi Alfred, all,

> > I have one prize coil wound with Litz wire (3" dia). The litz wire 
> > was a bargain basement reel costing $5. Unfortunately, the reel had 
> > two lengths on it which necessitated a solder joint about half way up.
> > The coil is heavily varnished and that joint has never given a 
> > problem or issued corona. The coil was giving 3' sparks at the time a 
> > crook cap set fire to it at the base.
>  
> Thanks Malcolm! It looks like I will have to wind an experimental 
> coil again with multible breaks and solder each and then give the 
> whole coil a couple of good coats of polyethylene and see if it works 
> like yours and the few others I have been hearing about. BTW Malcolm, 
> you said Litz wire! Hmmm I was under the impression that Litz wire 
> didn't do as well as one would think on a Tesla coil?

It's best in the A.M. broadcast range of frequencies (i.e. typical 
mid-hi TC freqs. Skin effect is almost non-existent because the 
strand diameter is caomparable with or less than 1 skin depth.

> What were you doing with it to get three feet sparks?

The primary energy was around 1.5J or so with PRF = 100Hz. It really 
sang (until it caught fire :(

> How long was that coil too?

Winding length about 16" with a 9" sphere mounted a couple of inches 
above the top of the winding. Not record breaking stuff, but I'm 
keen to fire it up again when the caps re-arrive. The experiment 
ended after 5s or so last time :(

Malcolm

BTW, I'm currently making a version of one of Tesla's early 1/2-wave 
lumped coils (a la the lecture to the AIEE) using modern materials 
and a slightly different primary configuration. It also has a ferrite 
rod for a core. I should be testing sometime this week.