Re: [TCML] Twin coils primary lead design

[DC Cox <resonance@xxxxxxxxxxxx>]

The best answer is to eliminate the lead inductance altogether.

One way is to mount the oscillator in an enclosure directly under the coil,
and the pri/sec is supported on the ends with 3/8" acrylic --- sort of like
a pedestal arrangement.

Dr. Resonance






2009/8/1 Peter Terren <pterren@xxxxxxxxxxxx>

> I am working on a small twin coil system with a cylinder primary and small
> spherical topload. Using a single coil only, run by a single MOT SISG, it
> puts out a 60 cm spark for a 50 cm secondary winding.
> I am finding results a bit limited when run as a twin system due to the
> length of the primary leads.  With a series primary arrangement I should
> tune to 3 turns on the primary but with loose leads this drops to about 1.5
> turns which is not efficient and spark length is less than 30cm despite
> double the power.
> With parallel primary windings, I should tune to 6 turns but it is reduced
> to 3 turns with the lead in wire inductance. It seems like I am wasting half
> of my inductance.
> Best performance of 90cm sparks with 2 MOT SISG is with a reduced tank
> capacitance to allow greater inductance in the primary using 8 turns in
> parallel connected primaries with lead in wires taped together sort of
> transmission line like.
> My question: How can I minimise the effect of primary lead inductance.
> Should I use two close parallel conductors (sort of transmission line like)
> or would a coax arrangement be better?  I can make up a coax system with
> copper pipe and plastic tubing covering 1/4 inch tubing. I don't really
> understand the concept of impedance matching as applied to Tesla coil
> primaries though or whether it is even likely to be relevant.
>
> Any thoughts?
>
> Peter  www.tesladownunder.com
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