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Re: 1/4 Wave, etc.
From: Alfred A. Skrocki[SMTP:alfred.skrocki-at-cybernetworking-dot-com]
Sent: Sunday, September 14, 1997 9:21 AM
To: Tesla List
Subject: Re: 1/4 Wave, etc.
On Thursday, September 11, 1997 1:25 PM Greg Leyh
[SMTP:lod-at-pacbell-dot-net] wrote;
> 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 actually 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.
Your observations are indeed correct! On can achieve effective 1/4
wave length by loading a coil with capacitance, this is exactly what
is done in many radio antennas to keep the antenna down to a
manageable size. With simple Tesla Coils (not magnifiers) without the
heavy top loading you will find that achieving both 1/4 wave length
and resonance simultaneously will result in rather spectacular output
for relatively small amount of input power.
Sincerely
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Alfred A. Skrocki
Alfred.Skrocki-at-CyberNetworking-dot-com
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