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Re: [TowerTalk] loooong feedlines

To:, <>
Subject: Re: [TowerTalk] loooong feedlines
From: Jim Lux <>
Date: Mon, 03 May 2004 11:27:37 -0700
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At 10:11 AM 5/3/2004 -0700, Rick Karlquist wrote:
He used 4 wires to get a lower Zo, because he didn't
want to deal with 450 ohms.  Now that the 450 ohm
problem has well established solutions, I can't see
where 4 wires is worth the trouble.

Rick N6RK

I think that if you had a situation where you had to run the feedline very(!) close to something (that is, a distance comparable to the spacing of the wires), the 4 wire balanced line has a more "contained" field. The ultimate would be a braided cable with lots of conductors carefully balanced in position relative to all the other conductors, etc. I was looking into this when developing extremely low inductance, low loss, low electromagnetic force cables for pulsed discharges that needed to run inside a metal raceway.

Quadro-line has also been featured in one of the ARRL antenna compendiums.

As Rick says, though, I doubt that for any amateur radio kind of installation it would be worth it.

Also, it's hard enough to make a high performance balun. Trying to make a truly balanced transition for quadroline would be quite the challenge.

Jim, W6RMK


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