Re: the cure for racing sparks

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "D.C. Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<DR.RESONANCE-at-next-wave-dot-net>

> A second note is that you may be "overcoupled" which causes the
> "double-hump" on the freq, ie, splitting the res. freq. into two different
> freqs which beat against each other.  Try elevating your sec. coil. or
> moving your primary further out.  With this size coil we get 28 inch sparks
> (our model M-20).  The sec. is elevated 1 full inch above the primary coils
> horizontal plane and the pri to sec coilform spacing is also 1 inch.

This double-hump in the frequency response of a Tesla transformer always
occur, and is a fundamental feature of the system.
The beats seen in primary and secondary waveforms are caused by the 
presence of two (almost) sinusoidal signals at different frequencies at 
the same time.
A Tesla coil should work correctly with coupling coefficients up to 0.6,
where the two oscillations occur in frequencies with a 2:1 ratio, but
at this point there are serious insulation problems.
Even above this there are solutions with maximum energy transfer,
but the waveforms are quite different, approaching the operation of a
regular transformer.
Excessive coupling appears to be related to racing sparks, but (I think)
the most probable reason is just too small distance between the 
primary and the secondary, distorting the electric field around the 
secondary.

Antonio Carlos M. de Queiroz