> >... explain how "current
> >flows through insulators" in the term of displacement current.
> >It seems to me there is simply not enough displacement current in
> >the Delrin to worry about, if the insulators are spaced along the
> >line a reasonable distance.
>
> - The issues are RF voltage gradient, and dissipation-factor at the
> frequency thereof.
The issue is voltage gradient per unit volume and dissipation
factor. If the voltage is not evenly distributed in the insulator we
need to know the distribution also.
As to your comment about my saying "Delrin is a dumb choice for
core materials in an inductor", you are correct. You lifted that
out of context, so here's what I really said:.
"The change is phenomenal, but has little to do with the dissipation
factor of the material. Even solid Teflon would be a poor choice in
this application. Delrin a dumb choice because it melts and warps,
even if it doesn't get that hot. But then Teflon cold flows and could
deform without heat."
"Sticking any dielectric in the area of a coil greatly reduces
Q. Even PTFE. I want to make that clear."
Condemming a material from all use because it doesn't work in one
specific application is poor engineering. .060 thick Fiberglass PC
board works great in striplines for 2500 watt HF amplifiers, but
it can certainly fail in a 2.5 kilowatt open wire line. Does that
mean we should never use it in any RF application?
73, Tom W8JI
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