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Re: Coupling constant for 4.25" secondary
I had a coil of similar dimensions...
4.12" x 21" secondary wrapped with 22ga wire
30 degree primary using 0.25" copper tubing with turn to turn spacing of
6.0mm, (0.236"). The distance between the primary innermost turn and the
secondary was 1.25". The measurements were taken with the primary tapped
at 15 turns.
With the first turn of the secondary even with inner turn of the primary I
measured the coupling at K=0.15
With the secondary raised 1.5" I got K=0.11.
I now have a coil with a 6.25" secondary and a 15 degree primary but I
haven't measured the coupling yet. One of those projects for the future!
Jon
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Sunday, March 14, 1999 1:14 AM
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
>