Re: Coupling constant for 4.25" secondary

to: Gary

With small coils systems the best way to achieve a high coeff of coupling
(0.18 to 0.20) is to use edge wound copper strap which allows for a very
high density as opposed to copper tubing or wire.  We usually hit 0.18 with
our smaller systems and this is with a flat spiral configuration using
edgewound copper strap --- usually 5/8 inch wide.  It works for us.



-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Saturday, March 13, 1999 6:34 PM
Subject: Coupling constant for 4.25" secondary

>Original Poster: Gary Lau  12-Mar-1999 2058 <lau-at-hdecad.ENET.dec-dot-com>
>Hello All:
>One of the few things I have yet to optimize on my coil is the pri/sec
>coupling, though from what I've read, it can make a big difference in
>performance.  I've not had problems with racing sparks on the secondary.
>My coil uses a 4.25" dia x 23.5" long 22AWG secondary and a 15 degree
>conical .25" copper tubing primary, with .25" spaces between turns.  The
>innermost point of the primary is at the same vertical level as the first
>turn of the secondary and (only!) 7/8" horizontally distant.
>(complete specs & pix at http://people.ne.mediaone-dot-net/lau/tesla/tesla.htm)
>I've measures the coupling coefficient "k" two different ways with
>identical results:  0.139.  I just tried raising the primary up by 0.25"
>and that changes it to 0.144, but it doesn't seem that the start of the
>primary should be above the start of the secondary.
>I know that there are so-called magic values of k that make for the
>cleanest quench, the nearest one to my coil being 0.153.
>What I would like to ask is, for other coilers using 4.25" secondaries,
>what values of k have you achieved?
>Gary Lau
>Waltham, MA USA