[TowerTalk] US Tower TX489MDPL Coax Sidearm Question

[Kimo C. Chun]

Hi Dick:

On Sunday, 3 Aug, you wrote:

--snip--
>OK, yet another =very= basic question:  is the coax supposed to hang loosly
>through the sidearms so the entire weight of the coax is born at the
>top-most attach point or is the coax supposed to be secured at each sidearm
>to minimize the weight on any one point?
>
>The sidearms give the appearance you are just supposed to run the coax
>through their loops without any attachment, but I can't belive you are
>supposed to carry the entire hanging weight of a 90-foot length of coax
>from one attach point.
--snip--


I only have one tower experience in this area. I copied the US Tower side
arms for my crank up. I wondered the same thing....

My solution is this.

1. Too much strain to hang coax and "slip" through the lower arms.
   I attached the coax at each arm.
2. Don't want them to tangle going up or down.
   I offset each arm by 30 to 45 degrees as I went up so each level
   of coax will hang between arms in its own loop.
3. I am using RG-213/u and rotator cable - all stranded but don't want
   to kink or stress unecessarily.
   I used 2 ft. pieces of plastic cable loom (black corrugated thin
   plastic tubing with a cut down the length to allow cable to be placed)
   around the cables as they passed through the arm. I placed the cable
   fastener (in my case black plastic cable ties) around the loom, cables
   and arm guide and tightened. This loom stiffens and increases the
   bending radius of the cables as they sag and provides abrasion
   protection to the cables as they pass through the arm guide. I can't
   say what would be better suited for other weather locales (cold!)
   I am too cheap to use my coated / stainless steel "Band-its" that
   I sometimes use for work to attach cables to messenger wires, etc.,
   though they would certainly be the ideal cable fastener.

I don't know if this is right but it looked good to me so I did it. I am
in the 2-way radio business so these supplies are readily available to me.
Loom might be available from a custom car stereo install shop or a two-way
company. It comes in a variety of sizes typically from 1/4" to 1" plus.

In professional situations they might use cable supports that are
woven webbed wire netting with a loop on top for attachment. It is like
the Chinese finger trap toy. When stretched lengthwise it closes around
the cable(s) and holds it tightly. The steel loop is then attached to
the support point. They come in different size ranges according to the
cable size being gripped. These are also sometimes used to haul cables
through conduits. But, if the cable weight/tension is removed from the
device it will expand and may let go of the cable. They are available
from commercial electrical supply houses.

I also loomed the rotation slack loop at the top of the tower and used
polypropylene rope from the boom of the first antenna to support and hold
the loop away from the tower top so it won't abrade or catch on the wide
tower top corners.

I am curious about what more experienced people have to say about my
solution. Better suggestions?

Good luck.


Aloha,

Kimo Chun, KH7U

kimo@lava.net
KH7U@contesting.com



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