Re: Steel core elements

On Tue, 6 Feb 1996, Clifford.H.Kraft_at_att.com wrote:

>. . .
>Conclusion: In my opinion (whatever that's worth), copperclad wire
>should behave electrically almost identically to solid copper wire at
>HF and certainly VHF and higher frequencies.

There's just one caveat to this. If the wire has a small enough diameter,
the copper can be on the order of a skin depth or less thick at HF and
below, even though it's a sizeable fraction of the diameter. I once used
some small (0.1-0.15 inch diameter) 72-ohm cable for portable operation. I
later was startled to find that it had 4 dB/100 foot loss at 7 MHz. Because
the stranded center conductor has such a small diameter, it's made of
copper clad wire for strength. The individual strands were very small so
the copper wasn't very thick. I've found quite a difference in HF loss
between RG-174 (0.1" dia 50 ohm cable) with stranded copper clad center
conductor and cable which is identical except for having a solid copper
clad center conductor (and consequently thicker copper). I believe this is
for the same reason.

Roy Lewallen
Received on Wed Feb 07 1996 - 00:54:00 EST