Re: Need Secondary wire source

["Gregory R. Hunter" <ghunter-at-accucomm-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

At 12:09 PM 07/31/2000 -0600, you wrote:
>Original poster: "Chris Brick" <cbrick-at-rebelbase-dot-com> 
>
>Hi folks,
>
>The surplus magnet wire has let me down once again.  Two secondaries lost 
>to between turn dielectric breakdown.  Does anyone have a good source for 
>double formvar or better wire?  I have found some quadruple coated wire 
>(may be overkill) but can't find a supplier that will sell by the pound.  I 
>need about 5 pounds of 22 gauge asap.

I don't think your wire is the problem.

>
>Here are the specs on my coil:
>
>15/30 NST overdriven to saturation, then backed off a bit with variac
>4 boards of 18 .056 1600VDC Panasonic caps in parallel for .0124
>Adjustable spark gap with 7 gaps, air blown across to help purge ion cloud
>14 turns of .25" copper pipe spaced .25" at 15 degree bank, inner turn is 7 
>inches
>It is tapped at about 8
>4x24 secondary on thin wall PVC drainpipe, dried and urethaned inside and 
>out and after winding
>6x20 toroid mounted directly to the top of secondary
>
>To date I have had two secondaries start to burn between windings.  My only 
>guess is the enamel on the surplus wire is not thick enough.  The burns 
>have happened in various areas on the coil, usually near the center and 
>start as a tiny black spot between two windings.  The coil runs very well, 
>giving me 36" streamers to air and sometimes streamers that almost hit the 
>ground (about 44").  I have 2 more identical 15/30 NSTs and will be 
>connecting them in parallel as soon as I get the secondary issue fixed.

Sounds to me like the coil is over coupled.  Try raising your secondary up
a few inches.  Better yet, build a flat spiral primary to reduce coupling.

>Thanks for any pointers,
>
>Chris
>
Best Regards,

Greg