Re: Help! Suicidal Secondary

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

Original poster: "James B by way of Terry Fritz <twftesla-at-qwest-dot-net>" <zebulan123-at-yahoo-dot-com>

Welcome to the list Winston
 I have experienced this problem in the past with my
22" x 3" coil it will put out 5'+ sparks but i must be
very carful or sparks races up and down the side"over
powering the thing" The only recourse that worked for
me short of lowering the power was to use a small
toroid as a corona shield and place a few breakout
lumps ,not points, on my monster top load. a smaller
total top load stoped my problem as well, but the
sparks were shorter then. hope this helps.
                 James
--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Bert Hickman by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>
> 
> Hi Winston,
> 
> If reducing the coupling doesn't seem to fix the
> problem, you may be
> overvolting the secondary. Try using a longer
> secondary winding (say 30
> - 32"), drop the wire gauge down to say #24, and use
> "double build"
> (2-layer) wire insulated magnet wire. This should do
> the trick!
> 
> -- Bert --
> 
> -- 
> Bert Hickman
> Stoneridge Engineering
> Email:    bert.hickman-at-aquila-dot-net
> Web Site: http://www.teslamania-dot-com
> 
> Tesla list wrote:
> > 
> > Original poster: "Marry Krutsch by way of Terry
> Fritz
> <twftesla-at-qwest-dot-net>" <u236-at-earthlink-dot-net>
> > 
> >     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.
> 
> 
> 


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