> Shape does matter, though..It's not just surface area. The
same amount of
> copper as a flat bar will have a different inductance (I
think less) than
> the same thickness of copper rolled into a tube.
Flat strap confines high frequency current mostly to edge
areas. That means you in effect have two parallel much
smaller conductors separated by distance. This increases RF
resistance over the same width in round shapes, but
> One can also go to extremes like Litz wire.
Litz wire generally has no less inductance and has MORE
resistance loss in HF applications than a solid wire the
same outside dimensions.
The advantage of Litz wire is in lower frequency multi-layer
coils where magnetic flux creates eddy currents in the
"copper" used in windings. At frequencies below perhaps
several hundred kHz Litz wire can reduce eddy current losses
enough to more than offset the increased conductor
resistance caused by stranding the wire.
The biggest mistake Hustler made (besides large metal
end-caps on coils) was using Litz wire in 75 meter KW
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Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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