Re: Coil design questions.

In a message dated 12/4/98 3:44:22 PM Mountain Standard Time, tesla-at-pupman-dot-com

>  A basic question for you seasoned coilers:  why is a the flat spiral
>  and lower coupling coefficient, better than a vertical helix or inverted
>  cone??  Seems sort of counter-intuitive . . . don't you want to maximize
>  coupling?  thanks.
>  Larry
    A Tesla coil works best when the coupling coefficient is about 0.2.  The
cone and helix can provide too much coupling too easily.   When the primary
and secondary are overcoupled, the output splits into two frequencies equally
separated from the resonant frequency.  This usually results in constructive
and destructive interference which creates high and low nodal points along the
secondary.  It is one of the  causes for arcs along the secondary that can
ruin the coil.
Hope this helps,