I'm trying to design a coil that will be used in a 1500 watt filter at HF.
I know that I need to allow for frequency related skin effect that will
reduce the area of the wire or tubing carrying the current.
First, I check the ARRL Handbook and the Antenna Book. No formula and no
table showing suggested wire sizes for a given frequency and power level.
Next, I determine that the skin depth at 28 mHz is .0005", and I calculate
the copper volume that the current is traveling through at one skin depth in
wires and tubes of various sizes. I get results that seem unreasonable -
using a current density of 2500 amps / square inch I get a current capacity
for #14 wire at 28 mHz of under .5 amps and for 1/2" tubing of just a couple
of amps. Yes, I realize that the skin depth is one standard deviation, but
even allowing for that the capacities seem very low.
Can someone point me at either a formula or a table that will tell me or
allow me to calculate what the current capacity of a wire or tube is at a
given HF frequency? Or, I suppose to put it differently since the capacity
is related to the acceptable temperature rise - something that will tell me
the copper loss in a piece of wire or tubing at a given frequency?
Thanks!
***dan, K6IF
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