Re: How to rise the secondary? (fwd)

---------- Forwarded message ----------
Date: Fri, 10 Jul 1998 05:47:05 +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)

  To All -

  Why are coilers building Tesla coils and raising the secondary to make
them work properly? Raising the secondary of a properly designed and tuned
coil only reduces the output. Why use a faulty design of excessive
overcoupling then try to correct it by raising the secondary?

  If a proper pri/sec clearance is maintained to prevent flashovers and the
coil properly tuned raising the secondary is unnecessary. Tweaking is part
of the tuning process and not necessary for coupling selection with a
correct design. With a properly designed TC the quenching adjustments relate
only to the primary circuit. Quenching always occurs after the first
transfer when the secondary circuit has almost zero energy and has no effect
on the primary circuit.

  Critical coupling is the same for Tesla coils as it is for any dual
coupled RCL system. If this condition can be determined at the time of
design the correct amount of overcoupling can be determined and excess
overcoupling avoided. It does not make engineering sense to deliberately and
incorrectly design a coil with excessive overcoupling and then try to
correct it by raising the secondary.

  I have studied and researched this problem with over a dozen coils. My
conclusion was that raising the secondary was not necessary with a properly
designed TC. In fact a TC that requires raising the secondary can never be
adjusted to produce optimum output. This is because moving the secondary
away from the primary will reduce the output. I have not solved the problem
of finding the exact coupling for a particular TC. However, coupling is not
critical as it does not affect the amount of energy transferred. Only
sufficient pri/sec clearance is required to prevent sparkovers. I agree more
research is needed.

  John Couture