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Re: Hot spot



Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Tesla729-at-cs-dot-com>

In a message dated 1/26/03 11:48:11 AM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:
>Hello Coilers,
>
>I ran my coil briefly yesterday and had an odd occurance.  After ten or
>so seconds of run time at very reduced power a hot spot developed about
>five or six turns up from the bottom of my secondary.  The run wasn't a
>normal one in that the coil sounded "rough" and the safety gap firings
>where more frequent, but the streamers seemed their usual length for
>the power I was running.
>
>After shutting down and safing the coil, I examined the secondary and I
>found an area where the epoxy resin appeared to have been burned off by
>heat but with no charring.  The exposed turns seem intact save for some
>of the coating being missing.  There was no indication of an arc-over
>to the inner primary turn which is about an inch away, nor had I seen
>such an arc when this hot spot appeared.  The hot spot looked like an
>orangy-green ball about half an inch in diameter and was quite bright.
>
>Any ideas as to what caused this?  Any suggestions as to measures that
>I could take to prevent a re-occurance?  The configuration of the coil
>was exactly the same as I've been using for months with no problems.
>
>73, Weazle, VE3EAR/VE3WZL



Weazle,

I've experienced a very similar occurance with my pole pig coil
before I finally got the primary/secondary coupling properly set.
I'm not sure this is exactly what you're seeing but in my case,
it was turn-to-turn flashover in the lower part of the secondary
coil. My coil was not running any "rougher" that I could tell when
this occured with me though. And the fact that you were not
running your coil any differently than before is a little puzzling. Once
I finally got the coupling properly set, I no longer experienced this pro-
blem and haven't since. And I've ran my coil in a myriad of atmos-
pheric conditions with temperature and humidity ranges from 10*F to
105*F and around 20% to 100%, respectively.

Try reducing your primary/secondray coupling and see if the problem
persists. If this isn't the problem, then I'm baffled, too :-P

Sparkin' in Memphis,
David Rieben