Re: Help! Suicidal Secondary

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Winston,

All I can think of is that the primary to secondary coupling is too high.
By raising the secondary you can lower the coupling which will stop the
racing arcs on the secondary.  If you have already done this, you might
find the actual coupling number with the following simple program:

http://hot-streamer-dot-com/TeslaCoils/Programs/MANDKV31.ZIP
http://hot-streamer-dot-com/TeslaCoils/Programs/MANDKV31.PDF

By knowing the actual number, that may help us figure it out if this
problem is a tough one.  Perhaps someone else will have further ideas.

BTW - You posted it fine :-)

Cheers,

	Terry


At 10:08 PM 1/5/2002 -0800, you wrote:
>    Hi everyone.  I'm very new to this, so I have a problem.  I built a
>6 inch coil using two of the infamous GE copier xfmrs as a power
>supply.  The coil works well (5 ft streamers), BUT....  I have long, hot
>sparks running the length of the secondary.  My first secondary for this
>coil was 6" by 22" with about 1400 turns.  This burned up, since it was
>badly built.  I just wound a new one which is 6.5" by 28" with 1200-1400
>turns, and it does the same full secondary arcing.  Coupling doesn't
>seem to make a difference.  The coil is tuned to the best of my
>ability.  I just put in a better RF ground, and this seems to agravate
>the problem.  The only time this arcing does not occur is when the coil
>is run in moist air, when there is condensation on the secondary.
>Putting a breakout point on the toroid helps, but won't eliminate the
>problem.  My toroid is 8" by 22", by the way.  The coil is coated with
>large amounts of polyurathane varnish, and holds a static charge after
>each run, if that helps.  Also, these sparks run directly on the
>secondary's surface.  They punch holes in the varnish with ease.
>
>Here are my specs:
>-6.5" approx. diameter by 28" secondary with around 1350 turns of 26awg
>wire, wound on thick wall white PVC.
>-8" by 22" toroid, whose bottom is 4" above the top of the sec.
>windings.
>-Primary with an IR of 4", and inter-turn spacing of 1/2" (C-C), tapped
>at 8.25 turns
>-0.1uF MMC array
>-Single static SG with a large 240VAC blower.  Gap set at 1/4".
>-2 wirewound 500 ohm resistors as chokes (probably inadequate).
>-2 GE copier trannies in series.
>-Runs at a freq. of around 100kHz.
>
>
>This is my first post, so if I did something wrong let me know.
>Thanks in advance,
>    Winston K.
>