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Re: 1/4 Wave, etc.
From: Greg Leyh[SMTP:lod-at-pacbell-dot-net]
Sent: Thursday, September 11, 1997 1:25 PM
To: Tesla List
Subject: Re: 1/4 Wave, etc.
Alfred A. Skrocki wrote:
> Hi Pete, a 1/4 wave coil is a coil such that the length of the wire
> wrapped around the form is 1/4 the resonant frequency of the
> finished coil.
[snip]
> BTW it is not as
> easy to make a coil 1/4 wave length as it would seem! There are many
> factors that alter the resonant frequency of the coil and these are
> very difficult to account for before the coil is actualy wound, but
> when it is achieved the results are usually spectacular! The most
> important of these factors is the combined distributed capacitance of
> the finished coil and it's top terminal.
It does not seem that the sec wire length makes an appreciable
difference in the performance of a standard TC.
I have noticed in PSPICE that typical TC secondaries with even moderate
top loads do not exhibit any significant standing wave behavior, but
operate more as simple LC resonant circuits. The voltage profile for
a normal TC along the sec is roughly linear, and only when the secondary
becomes coarsely space-wound with no top load does the voltage profile
start to bend into a quarter-sine.
This explains why Richard Hull and others have discovered that more
top load is better, with no discernable correlation between the
operating frequency and the electrical length of the resonating coil.
-GL