secondary suicide?

From:  Jeff Corr [SMTP:corr-at-enid-dot-com]
Sent:  Monday, April 13, 1998 3:58 PM
To:  Tesla List
Subject:  Re: secondary suicide?

Alot of other questions I forgot to mention I shall answer here :-)
The coil has been operating for almost 5 months without anything
like this before.  I have a GREAT RF ground.  I prepped the tube with
all the basic stuff, dried, heated, poly, etc.

Well now you probably have also read that I just got mad at the coil
and took an axe to it.  Just the secondary and primary that is.  I am going
to build a new primary with copper tubing, and a new secondary with #22
instead of #24 (which was a problem all in its own).

Either way I am still out of a coil for the next month or so.

>Sorry to hear about your secondary's self-destructive tendencies! How
>did you prepare your coilform prior to winding, what gauge/insulation
>magnet wire are you using, and what are the diameter and active coil
>length of your secondary? Also, what's the capacitance of your primary
>cap, and the power level (or faceplate voltage/current rating) of your
>HV transformer? 
>Offhand, I'd suspect that you may be getting arcover to an improperly
>prepared coilform. Alternatively, you may be inadvertantly overvolting
>your secondary if it is too short for the power level you're running at.
>Maximum turn-turn voltage stress occurs in the lower half of the
>secondary, so if you have insufficient voltage stand-off capability, it
>will show up here first.  Providing the above information should help us
>determine the cause.
>-- Bert --
>Tesla List wrote:
>> ----------
>> 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).  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/