RE: double wound secondary (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 04 Oct 2007 02:00:09 +0000
From: sparktron01@xxxxxxxxxxx
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: double wound secondary (fwd)

Hi Gary, Ed

NO, I'm not saying a two layer coils has 4X the inductance of a single layer coil.

What I am saying is a close wound double layer coil will have an inductance 
approaching 4X the inductance of a BIFILAR wound coil.  The adjacent turns 
of the parallel coil causes a 1X wire diameter space winding effect, that is
not present with a two (or more) layer close wound coil.

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA

 -------------- Original message ----------------------
From: "Tesla list" <tesla@xxxxxxxxxx>
> 
> ---------- Forwarded message ----------
> Date: Tue, 2 Oct 2007 19:01:31 -0400
> From: "Lau, Gary" <Gary.Lau@xxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: RE: double wound secondary (fwd)
> 
> Hi Dave:
> 
> Do I understand you to say that your two-layer coil exhibits 4X the
> inductance of the single layer coil with the same wire size and
> geometry?  This doesn't sound right.  Let's do a thought experiment,
> taking the concept of parallel conductors to an extreme.  What if the
> coil was wound with Litz wire, with tens or hundreds of identical
> parallel conductors?  I don't believe that the inductance there would be
> any different than if it were wound with a single conductor the same
> diameter as the Litz bundle and the same number of turns.  The Q would
> no doubt be higher, but it's not clear that secondary Q is critical once
> breakout occurs.
> 
> Regards, Gary Lau
> MA, USA
> 
> > From: sparktron01@xxxxxxxxxxx
> > To: Tesla list <tesla@xxxxxxxxxx>
> > Subject: RE: double wound secondary (fwd)
> > 
> > Antonio
> > 
> > Gary Weaver has posted several times (and I have built)
> > a "multiple layer" coil that is not specifically a bifilar wound
> > coil.  Wind one layer _close wound_ then wind another
> > layer on top of and in "groves" between adjacent turns
> > of lower winding layer.
> > 
> > By careful arrangement of individual wire entrance and
> > exit into windings, maximum winding error of only +/- 1 turn
> > (much less is practical) will occur.
> > 
> > I have wound such a coil with two layers, and have noticed
> > a MUCH higher Q then a typical "bifilar" wound coil.
> > Inductance is ~4X higher to boot.  In this case, it is equivalent
> > of two coils close wound in parallel, R would approach
> > R/2 (proximity effects will make it larger, but still significantly
> > less R then a single winding coil).
> > 
> > Band pass testing with two winding coil revealed a bandpass
> > so narrow, I could not fine tune VFO to maximum response,
> > it would "jump" either side of response peak.  Gary noticed
> > large improvement with two windings in parallel, less
> > improvement from 2 to 3 layers in parallel.
> > 
> > My coil was used on a VTTC powering a CO2 laser.
> > 
> > Regards
> > Dave Sharpe, TCBOR/HEAS
> > Chesterfield, VA. USA
> 
> 
>