Re: AWG vs. Diameter

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Jim -

How about welding cable? It's noted to be good for moving rf to ground
considering the hgih
quantity of thin strands. Might also be good in the primary (granted, it's
physically large, but
there might be smaller similar bundles).

Bart

Tesla list wrote:

> Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
>
> It occurs to me that a primary wound with several parallel smaller wires
> might actually work better than a "skin effect" equivalent crosssectional
> area tube or single wire.  Consider that you were to stack (vertically) a
> half dozen AWG 10-14 wires, separated by, say 0.1 inches, and wind the
> primary using the "ribbon".  Since the wires are physically separated, the
> self inductance (which relates to skin effect) would be reduced (much as
> "bundling" does for HV transmission lines).  One could even work out some
> sort of "braiding" so that each conductor spends the same amount of time on
> the "surface" (essentially what's going on with Litz wire), or stagger the
> various spiral layers.
>
> One might also be able to figure out a winding configuration that reduces
> the amount of loss on the inner turns: Say the cross section of the whole
> primary were thick in the middle and thin at the edges... like a spiral
> galaxy viewed edge on.  In the multiconductor scheme outlined above, the
> vertical spacing between windings would be greater in the inner turns than
> in the outer.
>
> .
> >
> > Then, as the recent discursion about the inner turns getting hot showed,
> we
> > have to consider proximity and eddy current effects.  Unfortunately, I
> don't
> > have an answer there.  I would think the thinner wire would be better, but
> I
> > don't really know.
> >
> > In general, people tend to find that the thicker tubing does better than
> > thinner wire.  We always attributed that to the differences in skin depth
> but
> > these new proximity and eddy current factors may matter a lot too.
> Primary
> > losses can really eat up a coil's performance so this is pretty critical
> stuff.
> >