FW: potential gain vs. power in TC systems

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Hi John,Et Al
I too am building a 12" coil. Do you think it would be pushing the ratio to
go 72" 6:1. 18AGW magnet wire. I was planning on going to .5" primary to get
more diameter but I'm not sure what this does to the comparative inductance.

Is it true that a torrid is best designed at a 3:1 ratio thus 60" would seek
a 20" minor diameter? DC if you are reading this please share how you make
your chicken wire torrids!

Regards,
Jim Mora

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Friday, April 07, 2006 3:38 PM
To: tesla@xxxxxxxxxx
Subject: Re: potential gain vs. power in TC systems

Original poster: FutureT@xxxxxxx

In a message dated 4/7/06 1:19:15 PM Eastern Daylight Time,
tesla@xxxxxxxxxx writes:


>Good point John.  Im wondering if losing some of the L is part of Z
>matching to the larger top load.


Gerry,

I really don't know.  There are others such as Paul N who have
more knowledge of this than I do.  But in any case I think
a 12" x 60" coil would be a good size and aspect ratio.  Using
more turns on the secondary permits more turns on the
primary for a higher primary surge impedance which should
reduce gap losses unless they would be low enough even
with lower inductance.  As the primary gets smaller in
diameter (to match the narrow secondary), then it seems like
more turns would be good, to keep the inductance high.
Whether any advantages to the lower surge impedance would
be offset by bad matching to the topload, I don't know.

In any case the secondary of Richard Hull's Nemesis classic
coil was 14" dia x 45" tall or so, and he got 15 foot streamers
using a 60" dia topload.  He used 18awg I think for about 1000
turns.  My guess is that he would have gotten the same
streamer length if he had used a 12" dia coil that was a little
taller or had thinner wire, but used the same 60" topload.

Richards streamers did arc down and strike the primary and
the base assembly below I think, due to the short secondary.
(He had limited ceiling height in the building.)

John


>I'm planning on a 12x60 inch coil.  To go larger than 12 makes the
>tube very expensive (unless sonotube is used) and I want to get
>height to help with strike rail hits.  My PIG is 5KVA that I hope to
>push to 8KVA.  Working on the rotor now so haven't put all the
>thought into the secondary that it will deserve.