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Re: H/D Ratios

```Subject:  Re: H/D Ratios
Date:  Thu, 22 May 1997 19:15:48 -0400
From:  "George W. Ensley" <erc-at-coastalnet-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.
>

>                   alfred.skrocki-at-cybernetworking-dot-com

Alfred,

I guess I sniped Too much of Malcolms post. Here it is again.

----------------------------------------------------------
>>Hi all,
>>        Following some discussion on this recently, here are some
>>theoretical findings which have been personally measured in practice:
>>
>>(a) max inductance from a single-layer helix : H/D = 0.45 or so
>>(b) max Q from a single-layer coil *with no topload* = 1
>>(c) max Q from a single-layer coil *with topload* = 2.5 - 3.5
>>
>>As a resonator gets larger, so too does the topload required to make
>>the wire 1/4 wavelength long.
>>
>>Malcolm
----------------------------------------------------------

I was refering to the difference in the electrical and physical 1/4
wavelength of a given piece of wire. One is not the other.

The measure its self is also in question as propagation  is different
along
wire than it is in free space. It is different still when wound in a
solonoid.

I often see importance attached to the physical length of wire used in a
tesla secondary. It would appear that Malcolm has done this in the last
two
lines of
the above post. I was wondering why?

George...
HAM=N4ZPO
SGMET=#244
FCC=PG-5-6642
erc-at-coastalnet-dot-com

```