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Tuning coils:Questions and Observations






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From:  Bert Hickman [SMTP:bert.hickman-at-aquila-dot-com]
Sent:  Sunday, February 01, 1998 7:38 PM
To:  Tesla List
Subject:  Re: Tuning coils:Questions and Observations

Tesla List wrote:
> 
> ----------
> From:  Matthew Mills [SMTP:mattmills-at-mindless-dot-com]
> Sent:  Sunday, February 01, 1998 12:35 PM
> To:  Tesla List
> Subject:  Tuning coils:Questions and Observations
> 
> Hi, I was reading with interest the post by (was it) Julian Green, about
> how one can tune the coil easily and safely using only 5 volts input
> into the NST (or 10volts here in New Zealand) and holding a fluorescent
> tube near the upper terminal. Well, I went home and what d'ya
> know.....it works!  I havent heard of this method before, why has noone
> else suggested this easy way?

With the gap firing with small gap spacing I assume = low power tuning.
If this is being done without the gap firing, then this is the first
time I've heard of this technique - please explain.

> 
> I have a range of coils wound by myself and by others, the ones wound by
> another guy "tune" when the primary is tapped at 18 turns which is quite
> high while my coil of similar dimensions tunes at the 5th turn  (this is
> with a top load).  This I have put down to his coils using a lot thinner
> wire and so have up to 2000 turns, while mine are quite thick wire
> having only 600-900 turns.

Your supposition is correct. Doubling the turns quadruples the secondary
inductance, halving the self-resonant frequency (all other things being
the same). 

> 
>  It is also interesting to note that his coils are wound anti-clockwise
> when looking down on them while mine are wound clockwise.  Does this
> make a difference?  I have never heard of a mention of direction of
> winding in all my texts on telsa coil building.

For simple 2-coil systems, it doesn't matter. 

> 
> While testing with only 10 volts going into my bank of 4 NST's i still
> managed to get 2 inch sparks emanating from the unloaded top wire!
> 
> Any answers to my questions or discussion on my observations?
> 
> Matt.

With small gap spacing and gap firing(?)...

-- Bert --