RE: Secondary Coil design

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

I have another observation that may be related.  I've noticed that the
innermost primary turn on my 15/60 NST-powered coil becomes detectably
warmer than other turns.  This after less than a minute of operation.
The primary is my two-layer primary constructed of 1/4" copper tubing.
There are no joints in the vicinity of the warming, and I don't know if
the two-layer design has anything to do with it.  The only explanation
that I can think of is corona between the affected turn and the
secondary, roughly an inch away.  I can't recall if I checked if there
was a similar heating of the lowermost secondary turns.  If 1/4" copper
tubing gets warm, perhaps the impact to a very fine secondary wire may
be more severe.

Gary Lau
MA, USA

>Original poster: "G by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<bog-at-cinci.rr-dot-com>
>
>Hello List,
>
>I have noticed a failure pattern in all of my secondary coils and am 
>searching for a solution. Each one has had a failure within the 
>bottom 25 turns (shorts between turns).During the most recent 
>failure, I was watching the operation very carefully in a dark room 
>and I am sure there wasn't any arc struck between the secondary and 
>the primary, or even corona.
>
>I have not noticed any other report of this problem. Has anyone had a 
>similar occurrence?
>I may try using a larger gauge wire toward the bottom to help deal 
>with the higher current in this region. Is current even the problem?
>Would using a larger gauge wire cause a damaging voltage gradient?
>Is space winding the bottom turns a possible solution? (also- 
>negative effect on coupling?)
>
>
>Thanks!
>Gregory