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

To: "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] Coax Loss -- RG-Numbers Don't Tell us Much
From: jimlux <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Fri, 05 Feb 2010 06:40:12 -0800
List-post: <">>
Roger (K8RI) wrote:
> Jim Brown wrote:
>> On Thu, 4 Feb 2010 10:38:19 -0800, Rick Karlquist wrote:
>>> 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.
>> Rick,
>> My point is that virtually all transmission line losses at HF are I squared 
>> R 
>> losses. 
> That's why you want to install the largest coax you can afford.

So, are we going to see articles in QST about "How to fabricate coax air 
line from thinwall 6" aluminum irrigation tubing" or " How I learned to 
stop worrying about rain on my openwire line and to love my TIG welder"


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