I have a US Tower HDX589-MDPL. Crank-up. My coax runs thru the rings on
the stand-offs. Because I ripped apart a Cat-5e and Siamese (RG59 & 18-2)
when raising it [I have four runs of LMR400-UF also in the rings] my
solution was to encase the entire bundle in "split-loom", used in engine
compartments to protect wiring. Works well. No problems. When I lower the
tower the bundle lays on the ground....and I am in Northern Maine :) cold
!!
I was told the LMR400 + ultraflex will deteriorate in sunlight. This
obviates that. Good luck.
73
Ivan
WK1W
Today's Topics:
1. Re: Tower and antenna decisions (Jim Lux)
----------------------------------------------------------------------
Message: 1
Date: Tue, 29 Oct 2013 08:25:57 -0700
From: Jim Lux <jimlux@earthlink.net>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Tower and antenna decisions
Message-ID: <526FD385.1010703@earthlink.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> Anyone care to advise me regarding issues relating to the coax run up
> the tower in the case of a crank-up tilt over with a rotating antenna
> atop it?
>
> 1. How do you keep the coax tangle and jam free when the rotator rotates?
A loop around the tower, or mast. Since the rotator only makes one turn (or
a bit more, depending on how the mechanical stops are arranged/geared), your
coax makes somewhere between N and N+1 turns around the tower.
> 2. What are the best choices for the part of the coax next to the
> rotator? Should all the moving coax be some kind of "ultra flexible
cable."
Maybe.. This is tricky because some ultra flexible cable gets there by
having a very soft dielectric, and then you have the problem of the
perpetual bend in the cable causing the center conductor so slowly migrate.
You'll get plenty of suggestions. Also, bear in mind how long you want it
to last.. if you are exercising your rotator once a minute for a year,
that's very different than twisting it a half dozen times over a weekend a
few times a year. Some people bring their antennas down every year to
change them or fool around with new designs. Some expect to put a piece of
coax up when they get their first rig at age 15, and whine when they think
it might have degraded, and now that they're 85, they can't climb the tower
any more to find out. (that's the beauty of ham radio.. it's incredibly
diverse!!)
> 3. How do you keep the coax from getting "messed up? when raising and
> lowering the crank up? I have heard there is a way to keep the coax
> inside the tower tangle free. Is that so?
hang it outside the tower?
There's several strategies..
a) One is to have little stalks that stick out with a ring on the end
through which the coax passes. as the tower retracts, the coax just slides
through the rings and piles up on the ground, perhaps in a tub.
A variant is some sort of spring loaded or motorized spool (think of a
cord retractor) to take up the coax (and rotator cables) as they come down.
The problem is that you then need some way to have a rotary joint or other
means to "untwist" the cables.
b) Another approach is to attach the coax to those stubs, so when the tower
is retracted, you have a bunch of vertical loops hanging in the wind.
both of these strategies also work "inside the tower", but there's more
possibility for thing to get tangled up.
You can also put springs or weights and pulleys on the loops in strategy
(b) to keep the coax from blowing around in the wind.
A lot depends on your environment. if you live in an icing area vs a
desert, etc.
>
> This is my first time so please treat me gently. I have never had a
> rotating ham antenna before.
>
>
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