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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