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RE: [BULK] - RE: [TowerTalk] 8X center migration in a coax choke?

To: 'Jim Lux' <>,
Subject: RE: [BULK] - RE: [TowerTalk] 8X center migration in a coax choke?
From: Steve Katz <>
Date: Wed, 17 Nov 2004 09:54:46 -0800
List-post: <>

> Wouldn't this then be something like RG-58?  The whole point of RG-8X, as
> I 
> understand it, is that the dielectric is foamed, and, so lower loss, 
> particularly at high frequencies.
> ::Yeah, at HF and even VHF the dielectric losses are too low to measure,
> so the loss is mostly from the center conductor: The fatter, the better.
> But RG8X "sized" cable with a solid dielectric would still be better than
> RG58/U, because it would still be fatter cable: .047" fatter, to be exact.
> Regular RG8X uses a #16AWG center conductor with a foamed dielectric.
> "Solid dielectric" RG8X would need to go to about #18 gauge, so for sure
> losses would be higher.  But still not as high as RG58/U.  Might be a
> reasonable compromise if strength is more important than loss.  Then, in
> those cases, I use Teflon coax, myself...-WB2WIK/6
> The impedance of a coaxial line is proportional to 1/epsilon
> *ln(Router/Rinner)
> The dominant loss in HF coax is resistive, and primarily from the center 
> conductor, so you'd want to have a bigger center conductor.  This would 
> make Router/Rinner a smaller number (and hence, the ln of the ratio 
> smaller).  To keep the same impedance, you'd want to make 1/epsilon
> bigger, 
> which means reducing the dielectric constant (epsilon).  RG-8X does this
> by 
> foaming the dielectric (so the overall epsilon is part air(gas) part
> plastic).

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