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Re: Fired, but need help

Patti,

This sounds like a symptom of overcoupling, although having your toroid
too high relative to the top of the secondary can also be part of the
problem, since it will tend to increase the local e-field at the top of
the secondary. Look very carefully at where you've sustained damage on
the secondary to insure that you haven't fused adjacent turns together
to form a shorted turn. Shorted secondary turns, particularly near the
primary, can overheat and carbonize your coilform. Any fused turns will
need to be removed, and a repair soldered in. Cover the repaired area
with a blob of epoxy, paraffin, or insulating dope.

To reduce coupling, elevate the secondary another 1-2". If you're using
an inverse conical primary, you may need to elevate the secondary a bit
more. Also, reduce the toroid height so that it's no more than 6-10"
above the top of your secondary. You may find that you'll need to retune
the system a bit, since this may change the effective topload
capacitance. 

Once you've verified optimal tune, run the system in a darkenned room,
and begin ramping up the power level. Look closely for any signs of 
corona between the top of the winding and the primary (sort of like a
Christmas tree..), or for any further inter-turn flashovers. At the
proper toroid-to-coil height, streamers should exit mostly horizontally,
after whick they may curve upward or downward towards the strikerail.
There should be no excessive corona coming off the primary or strikerail
or off the top of the secondary. Correct any problem area before
applying full power. 

Hope this helps, and safe coilin' to you!

-- Bert --

Tesla List wrote:
> 
> Original Poster: "Patti" <asrai-at-palmnet-dot-net>
> 
> Hello Listers,
> 
> This weekend the weather held out so I was finally able to achieve first
> light.  Results after safety gap, RSG, secondary height and toroid
> adjustments was 68" to a ground rod suspended on a ladder.  I did have a
> number of strike rail hits, so I raised the toroid up to a height of 18"
> above the top of the secondary.  My final voltage was about 196 VAC at 22
> amps to the 10KVA 14.4kv pole transformer that is current limited by a
> variable inductor with a range of .68 MH to 8.9 MH (setting was 6.9) and 2.9
> ohms of 10kw heater elements in series.
> 
> One problem though, and I need some help.
> 
> I'm getting numerous strikes along the outside of the secondary, starting
> with the top winding to the bottom winding.  Also I suffered some damage two
> turns about 5 inches up from the bottom of the secondary.  It got a bit
> cooked.  Right now I have the secondary bottom winding sitting about 1.25
> inches above the primary.  I'm running safety gaps at the caps at 1/2 inch
> and 5/16 inch on each side of the ground post tied to RF ground for the pole
> transformer. 
<SNIP>