[TowerTalk] Coax aging

Dick Green WC1M wc1m at msn.com
Wed Sep 3 00:00:42 EDT 2008

I've never been impressed with the jacket material used in LMR-400UF. Seems
way too soft, amd I think it either softens or gets brittle over time. Or
both. If the cable flexes at all, it's easy for the jacket to work loose
from the PL-259 threads, which eliminates the primary strain relief for the
shield braid behind the solder holes. 

I like Bury-Flex much better.

73, Dick WC1M

> -----Original Message-----
> From: Roger (K8RI) [mailto:K8RI-on-TowerTalk at tm.net]
> Sent: Tuesday, September 02, 2008 9:29 PM
> Cc: towertalk at contesting.com
> Subject: [TowerTalk] Coax aging
> I spent a couple hours on the tower this evening. The goal was to move
> one of the pulleys on top to the NW corner of the tower, install a
> second one at the NE corner, and then take down all the LMR 400 in
> preparation for installing the LMR-600. The last LMR 400 and LMR 400
> Ultra Flex was installed July 29, 2001 or just over 7 years.  The
> pigtails are still up there.
> The good surprise was  was every piece of tape used to hold 5 runs of
> coax in place was still good although there were a couple of pieces
> that
> looked like they'd been sand blasted. The not so good was the LMR 400
> Ultra Flex.  After just 7 to 8 years it was all bad.  Some of it had
> cracks 3 to 4 inches long in places where it wasn't even flexing below
> the top of the tower.  I haven't had a chance to look at the coils to
> see what shape the part that was flexing regularly is in.
> However after seeing the lower section of what's up there I'm going to
> order some Davis BuryFlex for the new pigtails.  Now I have two coils
> of
> LMR-600 UF (115' and 130') that probably aren't going up there.  It'll
> be interesting to see if any moisture made it past the connectors and
> into the regular LMR-400.
> Roger (K8RI)

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