secondary suicide?

From:  Thomas McGahee [SMTP:tom_mcgahee-at-sigmais-dot-com]
Sent:  Sunday, April 12, 1998 9:31 AM
To:  Tesla List
Cc:  corr-at-enid-dot-com
Subject:  Re: secondary suicide?

> From:  Jeff Corr [SMTP:corr-at-enid-dot-com]
> Sent:  Saturday, April 11, 1998 1:43 PM
> To:  tesla-2 list; tesla list
> Subject:  secondary suicide?
> Last week I ran into a problem I had never seen before.
> About an inch up from the bottom of my secondary,
> an arc started to appear when the coil was running 
> between 5-10 turns of wire.  This started melting the 
> PVC of course, so I turned it off and unwound the coil
> up unto that point, removing those turns.  All went fine
> until last night where the same thing occurred about
> half-way up the tube.  I put solder between the space which
> was arcing (about 8 turns).  

Barf Choke Gag! ***never*** short out secondary turns! 
The shorted turns will cause secondary power to be
wasted. It will adversely affect the output. If done
near the base of the coil, it can be disastrous!!!
A single shorted turn near the base will attempt to
consume all available electromagnetic energy. It is
dangerous. I can make a big circle out of thick solder
and place it in the center of my flat spiral primary,
and when I turn on the power the solder will melt
almost instantly. Dead shorts are bad news!

> I figured it would stop the arcing
> at least by shorting those turns out of the secondary.
> It did there, but 10 minutes later another "leasion" formed
> in another place on the tube about 4 inches below the 
> second one.  What is causing this??
> Jeff Corr
> 2114 Monitor
> Enid, OK 73703
> http://www.harvestcomm-dot-net/personal/corr/

The PVC insulation is being punctured, probably by what we usually
call racing sparks. This usually occurs when the coil is out of 
tune. The PVC insulation quickly carbonizes and conducts
afterwards even if the coil is now in tune.

Of course, it could also be that the PVC insulation is simply
breaking down do to overvoltage, and is not directly
related to mis-tuning. It's just that mis-tuning makes the
problem worse.

You may have to space wind the coil if the insulation is 
insufficient. That will allow some air insulation to intervene.
Filling the space in with several layers of varnish/etc.
would help even more. It sounds like your present secondary
is kaput.

What is your coilform made from? Was it heat-treated and/or
dried out and properly sealed before winding? Did you seal
the secondary after winding?  If you failed to do any of
the above, then moisture may be your culprit. This is 
especially the case when the coil form is cardboard or any
material that attracts moisture. Seal. Seal. Seal!

Hope this helps.
Fr. Tom McGahee