Re: Coupling constant for 4.25" secondary

to: Gary

k = 0.16 to 0.18 with the strap at .25 inch spacing on 18 turn pri.



-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Monday, March 15, 1999 2:16 AM
Subject: Re: Coupling constant for 4.25" secondary

>Original Poster: Gary Lau  14-Mar-1999 1703 <lau-at-hdecad.ENET.dec-dot-com>
>>>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
>>Original Poster: "Dr. Resonance" <Dr.Resonance-at-next-wave-dot-net>
>>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
>>our smaller systems and this is with a flat spiral configuration using
>>edgewound copper strap --- usually 5/8 inch wide.  It works for us.
>Hi Dr. Resonance
>Thanks for the tip.  This was something I was wondering about - primary
>geometry vs coupling.  A while back, there was a brief thread about using
>two-layer primaries.  It sounds like both the edge-wound and two layer
>techniques achieve the same thing - concentrating the primary in a
>smaller volume, and presumably, that achieves a higher k.  I assume that
>some kind of insulation is necessary between strap turns, and that
>varying the tap point is somewhat less straightforward than with tubing.
>I may opt for the two-layer approach (since I don't have a source of
>copper ribbon), and I'll probably make a dry run using just some 22AWG
>wire to test the inductance and k before building the real thing.  I
>assume wire gauge won't affect L and k if the spacing is like the final
>version.  It may be a while before I get to this, but I'd be interested
>if anyone has pictures on-line of either ribbon or two-layer primaries.
>Gary Lau
>Waltham, MA USA