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Re: [TowerTalk] Phillystran damaged?

To: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Subject: Re: [TowerTalk] Phillystran damaged?
From: Mike <nf4l@nf4l.com>
Reply-to: nf4l@nf4l.com
Date: Fri, 30 Oct 2009 05:08:27 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
It uses a thimble, and 4 clamps. I don't understand "if the cable is 
just placed under either the U-bolt or saddle". AFAICS, there is no 
other way to use saddle clamps than to place both sides of the cable 
between the saddle and the u-bolt.

Too late for advice on tension, this has been up for 5 years. ;->

I'm familiar with "Don't saddle a dead horse".

Mike NF4L

Roger (K8RI) wrote:
>
>
> Mike wrote:
>> My 4L SteppIR uses small diameter Phillystran as a bridle for the 
>> boom, clamped with saddle clamps. I have the antenna on the ground, 
>> and was going to replace the saddle clamps with stainless steel ones.
>>
>> When I took off the old clamps, the 'stran is crushed absolutely flat 
>> where the U-bolt side bore on it. It appears as tho there is nothing 
>> in the jacket. The jacket isn't broken, only flat.
>>
>> Is the Philly cut or broken, or is that much crush normal? It doesn't 
>> seem like a good idea to breach the jacket to have a look-see.
>>   
>
> The core of Phillystran is Kevlar (IIRC) and is made up of many fine 
> strands. When clamped that allows the jacket to flatten or distort 
> considerably without a great deal of loss in strength.  OTOH any time 
> you flatten a cable it loses some strength that varies widely between 
> materials.  The black jacket is purely weather proofing as Kevlar is 
> affected by water and Ultraviolet light.
>
> Using saddle clamps doesn't sound like a good way to attach the boom 
> truss if the cable is just placed under either the U-bolt or saddle. 
> I'm assuming you are using the small (1200# test) cable.  That is 
> normally terminated by using a thimble and three cable clamps. Use 
> sufficient tension on the cable clamps, but not enough to damage the 
> Phillystran. Don't crank the nuts down tight like you would on steel 
> cable.  Proper tension on the clamps will still noticeably distorte 
> the cable. That's why they use 3 with less tension instead of 1 or 2 
> that are tightened down more.  Remember the U-bolt" clamps on the 
> "dead side" while the saddle clamps on the side with tension.
>
> 73
>
> Roger (K8RI)
>> 73, Mike NF4L
>>
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>


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