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Re: [TowerTalk] Crappy LMR600

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Crappy LMR600
From: "Keith Dutson" <kdutson@sbcglobal.net>
Date: Thu, 24 Aug 2017 18:51:23 -0500
List-post: <mailto:towertalk@contesting.com>
I think you are referring to a direct strike.  I cannot think of ANYTHING
that could survive that.

73, Keith NM5G

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim
Brown
Sent: Thursday, August 24, 2017 12:53 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Crappy LMR600

On 8/24/2017 6:25 AM, Keith Dutson wrote:
> Turns out that lightning is also a major factor here.  A close strike 
> feeds secondary arcs to the tower and coax cables.  These arcs can 
> penetrate the coax jacket, creating pin holes that allow water intrusion.

Right. Good engineering practice is to bond the coax to the tower top and
bottom.  And control cables should be bypassed to the tower top and bottom.
The principle is to put the cables and the tower at the same potential along
their length.

>   Heliax is not ruined by this intrusion.

This is definitely NOT true. I rescued some 7/8" from a microwave site that
has the burns to prove it!  The reason it was there to be rescued is that it
WAS ruined by a strike -- the inside of the shield was carbonized!

73, Jim K9YC

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