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Re: [TCML] tank circuit power



On 5/19/2012 9:23 AM, Jim Lux wrote:
On 5/18/12 11:20 PM, Bart B. Anderson wrote:
On 5/16/2012 4:36 AM, Jim Lux wrote:

Heating depends on I^2R losses over time and
the heat that will occur on the primary at that inner turn or two if
very different for SG compared to SS. We can attempt rms numbers in the
primary, but if your gonna do that, don't leave out proximity effects
that occur from circulation currents from turn to turn and whatever
else.
I don't know that there's any extra current turn to turn, but there
probably is an uneven current distribution "around" the tube.

There are proximity losses of course and basic losses through the main
impedance of the primary. The can be all significant. For little coils
running basic NST's and what not, no, it's of no concern. It's always a
power thing.


What is the proximity loss? I would think that the current is the same in the inductor AND that the AC resistance doesn't change. Yes, the current is squeezed away from adjacent turns, but the effect on turn 2 (counting from the inside) and turn 8 should be the same (with constant spacing).

I think the inner turn hotter phenomenon might be more a matter of less cooling air flow (that is, it's "inside") rather than an uneven distribution of current or dissipation.
Hi Jim,

I don't believe for a second that air flow is the culprit. What I'm referring to regarding proximity loss are where the coils are mutually coupled and physically close to one another. My choice of terms is probably not the best. I'm not necessarily referring to turn to turn losses in the primary, but rather the magnetic field density where the two coils are physically nearest. That of course is the inner turn on a planar type primary. Would be nice to run something like JMAG on the situation (wish I had that software).

Take care,
Bart

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