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Re: Should I use a 4" or a 6" secondary? and a few more questions.

Tesla List wrote:
> 
> Original Poster: "Bob Berg" <berg_bob-at-hotmail-dot-com>
> 
> I'm triing to make up my mind on a few last details before I begin the
> construction of my first coil:
> I have 3 12K 60Ma NST's Thanks to Trent Mullins (mint franceformers!)
> :-)  that I will be using as a power source.  I will start off with a single
> NST and parallel as I feel more comfortable.  My question is should I be
> using a 4" PVC form with 24 Guage wire or a 6" form with 22guage wire.   The
> 4" route is cheaper and a little easier to obtain. But will the 4" handle
> the power of 12K -at- 180 ma? Or will I get better output with a 6" form.
> Second, if I build the coil properly, what kind of spark length output can I
> expect at 12K60ma, 12K-at-120ma & 12k-at-180ma
> using a RQ style SG?  Just looking for a ballpark, I know there are many
> variables.
> 
> The other concern I have is smoking my transformers.  They are so mint I
> afraid to smoke 'em. But I know its part of the game, and I have been
> reading so much about protection circuits and filters for NST's I'm confused
> beyond belief!  The only thing I feel sure of is a saftey gap.
> I'm afraid to ask the next question!:) Should I be using an L-C filter or
> R-C filter? gulp!
> Thanks
> Bob
> 
> ________________________________________________________________________
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Hi Bob!

If you plan on running off only one 12/60, you could likely use a 4"
form. If you plan to increase the tank cap size and running off two of
the NST's, I'd recommend using at least a 6" diameter form with about
28" of 22 AWG wire. This will provide you with a secondary coil that's
long enough to withstand the voltages you'll be developing at the
potential power level you'll obtain from a couple of NST's without
having a coil has too much of a "candlestick" form factor. 

However, if you are planning on powering the system off all three NST's,
you may want to think about using an even larger diameter coilform (say
8" or 10") and a longer secondary winding, since this system will be
fully capable of generating 6-7 foot streamers (especially if you match
the tank cap to the NST's at 0.04 uF). A 32-36" long coil may be
necessary, using 18-20 AWG so that you avoid overvolting the secondary
and to provide a reasonable secondary length:diameter ratio. 

Because of the direct addition of lossy elements, R-C networks should
provide significantly better overall protection than L-C networks.
Perhaps even more important, make sure that you have safety gaps going
between each HV leg of the NST to the RF ground. The safety gaps must be
physically very close to the NST's to provide best protection.

Good Luck, Bob, and keep us informed on your progress!

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
http://www.teslamania-dot-com