I use a similar method on my 72' US Tower MA-770MDP (that's the motorized
version, and I can't see it from the shack when it's raising and lowering.)
There's a standoff near the top of each section. The coax is attached to the
top standoff, but just drops through the rest of the standoffs. It sort of
lays itself on the ground in a random fashion, but never in such a way that
it tangles. It helps that the land slopes down very steeply from the base of
the tower -- the coax sort of falls down the hill.
I initially tried fixing the coax to each standoff to create loops, but it
quickly became apparent that this would not work. The loops tended to twist
on themselves and seemed likely to snag stuff like the pully sheaves when
the tower was being raised.
Even so, I had a near-disaster not long after installing the tower: when the
tower was almost fully extended, the coax got snagged on the motor housing
and the tower started to sway violently. Luckily, the SO-239 in the balun on
the antenna pulled out of the plastic housing (causing the balun to explode)
and released tension on the coax.
To prevent a recurrence, I did the following:
1. Switched from LMR-400UF to RG-213. Later switched to Bury-Flex, which is
actually more flexible than RG-213 and the jacket is more slippery for
running through the standoffs. LMR-400UF is *way* too stiff for a crankup.
When it hit the ground, the coax wandered around to the other side of the
tower and got snagged.
2. Added standoffs just above and below the motor housing. This keeps the
coax away from the motor. Probably using only one additional standoff above
the motor would have worked.
3. Reoriented the standoffs to be 180-degrees opposite the motor housing and
the tilt-over pulley.
4.Built a cage out of hardware cloth around the base of the tower to keep
the coax from getting into the rotor, rotor plate, mountings, etc.
This setup has worked well for 11 years. The only downside is that the coax
can get caught under ice and heavy snow. I typically pull it out soon after
a big snowstorm so this doesn't happen.
73, Dick WC1M
> -----Original Message-----
> From: Dick Dievendorff [mailto:dieven@comcast.net]
> Sent: Wednesday, January 14, 2009 11:54 AM
> To: 'Jim Garland'; TowerTalk@contesting.com
> Subject: Re: [TowerTalk] Cable management on crankup towers
>
> I have coax arms that just guide the coax, the coax isn't fastened
> except at
> the top coax arm (with Kellum grips). When the tower comes down, the
> coax
> gathers on the ground. I'm always out there to coil it. I didn't get
> a
> remote power switch because I WANTED to be out there when the tower
> went up
> or down.
>
> I saw a neat installation at N6EK's place. He had arranged the
> various coax
> cables with a slight twist, and when the tower was lowered, the coax
> coiled
> itself over a low barrel that he had arranged. Very neat. I've never
> seen
> it before or since.
>
> N6TV used a large swimming pool leaf net to collect the coax as it
> descends
> when the tower comes down.
>
> Dick, K6KR
>
>
>
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