# Re: JF efficiency theory (again)

```Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hello Mike,

On 18 Feb 01, at 13:58, Tesla list wrote:

> Original poster: "Mike Novak by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <acmnovak-at-msn-dot-com>
>
>
> http://hometown.aol-dot-com/FutureT/page5.html
>
> I was wondering why some coilers get such good results when completely
> disregaurding such details. For instance, Ross Overstreet's coil:
> 6"x24" wound with #22 for a total of ~880 turns, a primary of approx
> 7-8 turns (from the photo) and ~2.2kVA input along with a static gap.
> He gets 6-7 ft sparks which is just about right from 1.7(sqrt(input
> power)). However, he's only using half the reccommended number of
> turns on both the primary AND secondary. Is it possible that it is not
> the NUMBER of turns, that maybe it's simply proportionate on some
> level?

I agree with your conclusion. It is in fact the reactance nee surge
impedance that matters. Obviously, many different coils having 6-7
turns can be wound with large variations in inductance. Likewise, a
single 6-7 coil will have a wide range of reactance depending on what
frequency it is run at.

> Also, I Find that where people follow the 1600 turn rule they, more
> often than not, neglect the 24-34 primary turn suggestion. I
> personally don't see how one could always use 24-34 turns and still
> maintain a resonant condition.

You choose the primary capacitance accordingly.

How is anyone supposed to achive such
> high levels of efficiency if they must choose between resonance and
> high primary surge impedance? Are we just supposed to use thin wire on
> the primary? I once used two #22 wires in parallel for the primary on
> an early coil I made. It worked quite well too.

For a particular primary, you can build an infinite number of
secondaries and choose a primary capacitance to resonate the primary
with them.

> If we want high primary surge impedance, why does everyone concern
> themselves with using welding cable as tank wiring?

Surge impedance is primarily dependent on inductance. Ideally, you
want zero resistance in any winding to avoid copper losses.

Regards,
malcolm

> Mike Waddick and I compare notes often and he is using the 6x24 with
> #22 as well. Wouldn't the optimal wire guage be as follows?:
>
> diameter                guage
> 2                                 34
> 4                                 28
> 6                                 24
> 8                                 22
> 10                               20
> 12                               20
> 14                               18
> 16                               16
>
>
> Just trying to get more bang for my buck,
>
> -Mike Novak
>
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```