Check the archives if you get time, Roger, on the subject. It was well
aired a while back, and the best that I derived was to support the cable
with Kellem Grips at the top and then provide eyebolt, plastic(teflon or
Delrin) "bushings" in the eye to prevent the coax from hanging up on
metal during raising or lowering. LMR600UF is prone to do that, since the
rubber-like jacket is far from slick.
I don't understand the 2 loop provision for rotation - that can easily
destroy the cable, if it hasn't already. The suggested bend radius
offered by Times does not relate at all to the function of rotating
masts. A fellow TT'er has made a copy of a diagram of a method that
works that we can attach if your e can receive it.
holler if you need more help.
73,
Press Jones, N8UG, The Wireman, Inc., Landrum, SC, 29356
Sales (800)727-WIRE(9473) or orders@thewireman.com
Tech help (864)895-4195 or n8ug@thewireman.com
www.thewireman.com and the WIRELINE bargain page
Our 21st year!
On Sat, 11 Jul 1998 10:11:49 -0400 "Roger Rehr" <rrehr@epix.net> writes:
>
>I have a 72 foot crankup (US Tower HDX572MDPL)that was installed the
>weekend
>before the June VHF QSO party with the usual coax arms.
>
>I run 4 runs of LMR600UF plus rotor cable to the top. The mast is
>only 12
>inches above the tower top, and the horizontal member of the top coax
>arm
>was used to secure the coax with heavy cable ties and electrical tape.
>
>The tower is kept down at 23 feet except for when I operate, when it
>is
>taken to full height.
>
>The weight of the cables is such that
> 1. the cables are being compressed where they angle
>over the top coax arm
>to go to the boom.
>
> 2. The 2-turn safety loops to allow free rotation of
>the boom actually got
>pulled tight around the mast
> so that no rotation was possible.
>
>These problems were noted after an extended 10 day period at 23 feet,
>when
>the hanging weight of the coax would have been at its minimum (23 feet
>instead of 72 feet).
>
>Obviously I need another way to secure the cables at the top besides
>heavy
>cable ties to the coax arm horizontal member and 3M electrical tape.
>
>It would seem to me that a wide secure attachment to the top 6-12
>inches of
>the coax as it runs vertically just after it descends through the
>first coax
>arm, with this attachment suspended by a strong cable (just
>mechanical) to
>the first coax arm above would relieve the strain without compressing
>the
>coax.
>
>Anyone have any thoughts about how to solve this problem? I pulled
>out and
>read the "FORMING COAX ROTATION LOOPS" thread from late June as nicely
>summarized by Mark N1LO, but as my tower must rise and descend I can't
>distribute the weight of the coax along the tower; it must all be at
>the
>top.
>
>If there are very reliable commercial strain relief devices, that
>would be
>nice.
>
>Thanks in advance
>
>73 from
>Roger Rehr W3SZ ex-AA3QK ex-WA3JYM
>mailto:rrehr@epix.net FN20ah
>http://www.epix.net/~rrehr
>2 Merrymount Road, Reading, PA 19609
>610.670.8687
>
>
>
>--
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>Problems: owner-towertalk@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
>
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