Re: coupling (fwd)

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Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Tue, 24 Oct 2006 18:09:18 -0500
From: resonance <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: coupling (fwd)




Best way to do it is to use some scrap wire and slit some cardboards strips 
to hold the wire.  In this way you can configure a primary, measure the 
coeff of coupling using a hot water heater element, and then adjust it until 
you get it into the desired range of 0.18 to 0.20.  This provides optimum 
performance without engaging "racing sparks" effects.

I would guess approx 1/4 inch above horizontal plane of primary for the 
start of sec winding, but it would be prudent to check it out first prior to 
winding any turns of copper tubing.  You can also use scrap wire to set up 
15 turns and then tap down to the best resonant value --- do this before 
winding your copper tubing only to discover you have to make changes. 
Copper tubing work hardens and does not take well to repeated bending and 
forming.  Inexpensive 12 AWG stranded wire works good for any check and can 
be easily reshaped as necessary to set the proper coupling range.

Using a 4 inch OD sec I would consider going 4.5:1 height/dia ratio for the 
sec coil.  This produces an 18 inch long winding length.  Divide this 18 
inch length by 1,000 turns (optimum value for nst powered coils) which 
equals .018 wire dia.   This produces a wire guage of 25 AWG for your 18 
inch long sec winding.

You can use JAVATC online to do all the coeff of coupling "what-ifs" and get 
it real close.  In JAVATC you have to enter your coil radius values, base of 
coil height above the ground plane (usually base of your sub-base supports), 
and top height of coil from the ground plane.  Also required entry is the 
center of toroid to your ground plane (coil base) measurement.  It gives 
very accurate results but I would still set up the hot water heater element 
and actually measure it with some old wire prior to winding up the copper 
tubing.

Dr. Resonance


> Before I get to fancy making some nice lexan plates and ceramic stand
> offs to mount the secondary to be adjustable and look awesome.....
> what is a good coupling to start for a 4" diameter 10" wind secondary
> with about 12.3 turns of primary tubing?   start flush with bottom of
> secoundary? start 1" under secondary?
>
> Thanks.
>
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