Re: How to rise the secondary? (fwd)

---------- Forwarded message ----------
Date: Wed, 15 Jul 1998 18:28:11 +0000
From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: How to rise the secondary? (fwd)

  Greg -

  My program is for classical Tesla coils where couplings as high as 0.6 are
not appropriate. However, the program will accept couplings this high but
the pri/sec clearances are very small.

  Pity the ol' armchair programmer sitting there on his sketches and notes
bemoaning the fact that there are other coilers in the world that are
building and testing their coils and having all the fun.

  It is not possible for a coiler at this time to know beforehand the
ultimate quenching capabilities of their rotary gap. This is why quenching
is not a part of the JHCTES program or any other TC program. Rotary gaps are
5% design and 95% craftsmanship.

  The JHCTES program does not recommend a coupling value because this could
be misleading. The program, instead, recommends a pri/sec clearance to
prevent sparkovers for the design voltage being used. The clearance info was
obtained from empirical data supplied by coilers who built and tested coils
like you. The computer uses the clearance info to calculate the mutual
inductance and coupling.

  This still leaves questions about coupling and tuning and how these
parameters affect quenching of the gap. It appears that coupling and tuning
can not be separated when adjustments are made so quenching may be due to
either coupling or tuning or both.

  John Couture


At 02:55 PM 7/14/98 -0600, you wrote:
>---------- Forwarded message ----------
>Date: Mon, 13 Jul 1998 22:17:07 -0700
>From: lod-at-pacbell-dot-net
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: How to rise the secondary? (fwd)
>"John H. Couture" wrote:
>>   Coupling is not a critical adjustment for Tesla coils and exact coupling
>> is not necessary. In fact, when the secondary is raised if only the
>> coupling changed the only change would be a reduction in the TC output. The
>> reason the output does change is because the tuning changes and this is very
>> important and must be precisely set to obtain maximum output from the TC.
>What you say makes sense from a theoretical standpoint, 
>but _ONLY_ from a theoretical standpoint!  Otherwise,
>why doesn't your program suggest a coupling around 0.6
>or higher, to efficently transfer in a single cycle? 
>If one gets up from the ol' armchair and ventures to put
>actual equipment at risk, it is prudent (if not essential)
>to be able to alter the coupling.  How is it possible for 
>one to know beforehand the ultimate quenching capabilities 
>of their rotary gap?  The coupling value must accommodate
>the capabilities of the gap, to avoid excessive gap ablation
>and obtain maximum performance.
>Until your program can predict the quench performance of a
>given gap electrode geometry, you must necessarily be able
>to adjust the coupling in order to get optimum results.