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Re: [TowerTalk] 8X center migration in a coax choke?

To: "Rob Atkinson, K5UJ" <>,<>
Subject: Re: [TowerTalk] 8X center migration in a coax choke?
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Tue, 16 Nov 2004 19:42:17 -0500
List-post: <>
> I'd like to know if anyone makes a version of 8X with a
solid dialectric,
> or, if anyone has made a choke with this cable, on such a
tightly wound
> form, have you had a problem with the center migrating?
> I can always use a wider form but I have to admit that the
smaller pipe
> would be easier to adapt.


I use thousands of feet of the stuff and none of it is

I consider it cheap coax, so I'm rough on it. I have 300 ft
long hunks hanging from high dipoles (I have a 318ft tower)
and I don't worry. To keep the wind from blowing and
breaking the shield from the connector I just wrap #17 steel
wire right around the jacket tightly and tie it to a pipe
driven in the ground that supports my antenna switch.

As for chokes.... I've been using chokes made with RG8X for
years and never had a problem regardless of power level or
stress. I use 4" maximum diameter. My 80 meter antennas have
baluns over 10 years old. The ONLY problem is the white
center insulation has powdered up where it is exposed to GA
sunlight. I cut one back a few weeks ago until I got to new
foam. This time I wrapped the foam in coax seal.

The foam in every RG-8X I have seen is a pretty dense foam.
I typically measure a Vf in the order of the low 70's, so
that clearly means it isn't all that "foamy".

The only problem I've ever had with center conductor
migration has been in solid conductor cables with a
copperweld conductor and very sharp radius. I don't worry
anything at all about winding foam cables smaller than RG8
on 4" forms. I do it dozens of times a year and never have
had a problem.

73, Tom


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