I've got coax in use made by a number of manufacturers. Some is RG8 some
213, some other numbers and some unidentifiable. Most of the RG8 was picked
up in 1954 as surplus and some is still good and in use.
When I have a coax problem and it is not readily discernable I TDR it with a
Tektronix 1502. Pinpoints the problem every time. Just because coax is old
does not mean it is not good. The condition of the covering (no cracks, cuts
or other points for water to enter) is key.
When I moved from my PDX QTH to the OR beach, I did a nitty-gritty
inspection of all my coax and did find some older coax that had begun
developing cracks and tossed it. Outdoors from the house to the tower is all
new stuff. The beach environment beats the crap out of everything!!!!! The
surplus RG8 I have is now only used in an indoors environment and I have had
no problems with it in over 8 years and some of the old coax has full legal
limit RF being stuffed through it.
The TDR is an invaluable tool and beats guessing!!!
----- Original Message -----
To: "Tom Osborne" <firstname.lastname@example.org>
Cc: "Towertalk" <email@example.com>
Sent: Friday, August 27, 2010 8:56 AM
Subject: Re: [TowerTalk] Life expectancy of RG-213
Sounds like the jacket is NOT non-contaminating and has caused the problem.
Quite often, that occurs with CHEAP coax brands, especially those
'bargain box' brands that come from U-NO-WHERE.
I stick with Belden, Times, and other major manufacturers.
Some of the military surplus RG-213 is 10 or more years old and MINT.
When sold, it often has the end caps STILL ON IT. That's a good
indicator of quality, IMHO.
I bought a large amount of military surplus RG-213 with N-connectors,
and use the Female-N to Male-UHF when necessary.
Quoting Tom Osborne <firstname.lastname@example.org>:
> Hi Don
> What makes coax turn black anyway??
> I was checking some feedlines here and some off-brand RG8X I have and the
> center conductor and the sheild turned both black. It was not just at the
> ends but a long way back from the end.
> It doesn't look like it was wet.
> Looks like I'll have to get rid of a bunch of it. 73
> Tom W7WHY
> Beg, borrow, buy a TDR and look at it that way.
> Most coax will last many more years than people believe.
> Problems occur from moisture ingress, but, if trimmed when necessary,
> will do just fine.
> My rule of thumb is: If the shield is shiny, it's OK.
> I have 100's of feet of it ready to put into use this Fall/Winter season.
> Now all I need to do is get the towers/antennas up!
> Good luck
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