Re: Primary Heating

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Or even, here is a reason to use a "strap on edge" instead of tubing... It
increases the distance from adjacent turn....

Another idea... what about two stacked flat primaries, with larger inner
diameters, but with the same total inductance and coupling to secondary.

Another thing to consider about flat primaries is that they provide a form
of counterpoise for the top load as they essentially sit at "ground
potential" (at least on the scale of the secondary topload voltage)....
Perhaps separating the two functions might be a wise idea...  

primary winding in form of clump (with geometry of clump chosen to minimize
losses) of  windings at some distance (forming a sort of toroid), radial
strips of copper foil to form a ground plane connected to base of
secondary.  With clever design, one might actually be able to put the
primary under the ground plane, essentially removing the possibility of
primary strikes.

What about a tape wound primary, with a short "bar" core sticking up to
increase the coupling to the base of secondary? The core would increase
inductance, so you'd need fewer turns (less series R and proximity effect)

At some point, you're getting close to a classic resonance transformer hv
test set, where you have a smallish transformer driving a series LC circuit
to get the voltage up. (Sort of like a magnifier, eh?)




Tesla list wrote:
> 
> Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Gary.Lau-at-compaq-dot-com>
> 
> I wonder if a conical primary, where the inner turns are less under the
> influence of the outer turn's magnetic field, can be shown to have lower
> proximity-effect losses?
> 
> Since the losses necessary to heat up a significant length of copper tubing
> probably are significant, would the losses in a primary segment (just the
> innermost 2-3 turns, since Litz wire can't be tapped) constructed of Litz
> wire be significantly less?
> 
> Gary Lau
> MA, USA