RE: double wound secondary (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 3 Oct 2007 12:42:50 -0500
From: Terry Oxandale <Toxandale@xxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: double wound secondary (fwd)

I believe the rule is that two tightly coupled mutually inductive coils
of same polarity (which this appears to be the case) would have a sum
inductance equal to about the inductive value of one of the coils. So...

Terry

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx] 
Sent: Wednesday, October 03, 2007 8:59 AM
To: tesla@xxxxxxxxxx
Subject: RE: double wound secondary (fwd)


---------- 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