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Re: Topband: Ends for older Phillystran

To: "Bill Wichers" <billw@waveform.net>, <n2ic@arrl.net>, <topband@contesting.com>
Subject: Re: Topband: Ends for older Phillystran
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Tue, 14 Jan 2014 14:02:40 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
The bar idea would probably significantly reduce the allowable tension on the cable, similar to what knotting does, due to the force at each "bite point" weakening the cable. I suppose if the cable was sufficiently oversized this wouldn't pose a problem, but I'd certainly expect such a clamping method to effectively reduce the allowable tension significantly below the normal rated load.


I wouldn't do anything as tight as a knot, especially when both surfaces have significant yield. The holes would have to be chamfered to prevent cutting through the jacket. It wouldn't be much different than an insulator if done correctly. It is all about not making the short turn radius a knife.

I'm actually a little surprised a dead end / preform isn't supposed to be used with the straight-strand version of the cable. Those grips work by compression of the cable they are "grabbing", and it's a fairly even pressure over the length of the gripped area. If one could be found that was the correct diameter for the cable being used it might be worth a shot, but I completely agree with Tom -- TEST ANYTHING YOU TRY BEFORE USING IT FOR REAL! He's also correct that dynamic loading is much worse than static loading. Wind causes vibration in towers and guys and that can cause your clamps to loosen over time, especially if they were marginal to begin with.


There has to be considerable pressure on the jacket squeezing it into the inner fiberglass. I'd be reluctant to use a grip on something that has a tendency to slide. I don't think it will squeeze hard enough. The newer Phillystran has much less tendency to have the jacket slide over the center.
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