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Re: [TowerTalk] Coax Loss -- RG-Numbers Don't Tell us Much

To: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Subject: Re: [TowerTalk] Coax Loss -- RG-Numbers Don't Tell us Much
From: "Rick Karlquist" <richard@karlquist.com>
Reply-to: richard@karlquist.com, "Tower and HF antenna construction topics." <towertalk@contesting.com>
Date: Thu, 4 Feb 2010 10:38:19 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Jim Brown wrote:
. The lower the total DC resistance, the
> lower the loss at HF. Copper coated steel and copper coated Al have more

This is *generally* true, if comparing all copper cables.
But even in that case, the HF loss is not proportional to
DC resistance when comparing different sizes of cable.
And all bets are off when copper plating is involved.
It is also worth noting that Al has something like 1.6 times
the DC resistance of Cu but only 1.3 times the RF resistance.
Finally, 75 ohm cable has considerably more DC resistance than
50 ohm cable with the same RF loss.

Bottom line is that DC resistance is only loosely related
to RF loss.

Rick N6RK

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