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Re: H/D Ratios
Subject: Re: H/D Ratios
Date: Wed, 21 May 1997 04:48:23 +0500
From: "Alfred A. Skrocki" <alfred.skrocki-at-cybernetworking-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
On Mon, 19 May 1997 22:03:40 -0400 George W. Ensley
<erc-at-coastalnet-dot-com> wrote;
> I have seen several references to a physical 1/4 wavelength of wire
> being used to wind a secondary. What is the 1/4 wave length based on?
> Is it free space or based on some velocity factor? Is there some magic
> to be had by striving for this.
Hi George! There is nothing agical about the 1/4 wavelength rule, it
is based on the fact that at the 1/4 point in a wave is the voltage
maximum (see ASCII drawing below) since you want the top of your
coil to be the point with the maximum voltage, you make the wire for
the secondary 1/4 wavelength long. If you were to bottom feed a coil
that was 1/2 wavelength long the maxium voltage would occur in the
middle of the coil and there would be 0 voltage at the top (again
see ASCII drawing below). If you were to center feed a coil that was
1/2 wavelength long it would behave as if it were two 1/4 wave coils
connected bottom to bottom. If you were to make a bottom feed coil
3/4 wavelengths long it would have maxium voltage 1/3 the way up the
coil and at the top of the coil, and a 1 wave length coil would have
the maxium voltage at the 1/4 and 3/4 points. So you can see anything
other than 1/4 wavelength bottom feed or 1/2 wavelength center feed
in not only a waste of materials but you risk dammage to the coil by
having maxium voltage and conseguential coronal break out on the side
of the coil.
1/4
| |
| * *
| * *
*--------*--------*
| |* *|
| | * * |
|<--1/2->| * * |
| | |
|<----3/4--->| |
| |
|<-------1------->|
Sincerely
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Alfred A. Skrocki
alfred.skrocki-at-cybernetworking-dot-com
.ooo0 0ooo.
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