Topband: deterioration of RG-6

[Guy Olinger K2AV]

I would have to call this the true colors of RG6, given enough time.
I have had that problem with years old TV & SAT leads around here, and
am going to flooded RG6 on anything new, to prevent just what you
describe.  The oxidation is capable of creating impedance anomalies at
TV frequencies and extra loss at MF.  In one aged case after the
jacket was removed for inspection, just a mild flex of the remainder
split the foil, which clearly had become brittle.

My best guess is that the braid creates an ingress path that breathes
and contributes to condensation after time.

Splices and connections on regular RG6 need to be vapor sealed ala
RG8, etc to prevent what is otherwise an inevitable process.  Better
choice is to use cable and connectors intended for burying, and the
spec'd tools to crimp them.

73, Guy.

On Tue, Apr 6, 2010 at 8:18 AM, Pete Smith N4ZR <n4zr at contesting.com> wrote:
> I feed my 160m receiving antenna with about 300 feet of RG-6, which
> supplies power to an amplifier at the antenna.  Recently, I started
> seeing an high-resistance short across the coax (~30-50 ohms).  I took a
> junction apart and discovered evidence of current flowing across the
> double-female, as wellas some water in the connector.  I changed it out,
> and also changed both connectors on the cable, and in the process
> discovered that the braid and the first foil (it is quad-shield) appear
> to be somewhat corroded (there is a powdery grey residue that comes
> out).  I reconnected the junction, and within a few days both the short
> and the moisture were back.  In checking out the problem, I have cut
> back a couple of feet on the cable, and the grey residue is still evident.
>
> Is water ingress a known problem with RG-6?  Any particular brand known
> to be better?  If I'm going to replace the whole feedline I might as
> well do what I can.
>
> --
> 73, Pete N4ZR
>
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