[TowerTalk] USTowers and cables

Sat, 11 Mar 2000 12:55:31 -0800

Hi, Steve.

I'm surprised that no one appears to have responded to your question.
I have a US Tower HDX-572MDPL motorized crank up that I installed two
years ago.  I have four cables running to the top of the tower; two
eight-wire control cables and two runs of RG213.  The tower is lowered
and raised on average of once a week.

I have never had any hint of a cable problem lowering the tower and
with one simple precaution, I have never had a cable problem raising
it.  They key is that the cables must not be attached to the tower,
itself.  They need to be kept a protective distance away from the
moving sections by using the cable arms.

There are two schools of thought on how to utilize the cable arms.  One
says to attach the cables at each arm so they form big loops when the
tower is lowered.  The other says to suspend the cables from the very
top arm and let them slip freely through the others.

Personally, I don't like the first approach.  I don't like the bends
placed in the cables when they droop and I don't like the chance of the
cables catching on the arms as the tower is raised.  The primary
advantage of this method appears to be that the cables don't gather at
the bottom of the tower when the tower is lowered.

I prefer the second approach.  The hanging weight of 70 feet of most
cables and coax is far less than what would be required to stretch or
otherwise damage it.  The key is attaching the cables at the top arm in
such a way that they are not bent or kinked.  The second caution is
that the coax arm loops need to be treated in such a way that the
cables can pass freely through them without being cut or torn by rough
edges or sharp galvanizing points.

You can see a full chronicle of the installation at
http://www.qsl.net/w6old/party.html, but some specific photos might
help illustrate the process.

http://www.qsl.net/w6old/images/party/stack-hi.jpeg shows the tower
fully extended.  You will see how the cables are suspended away from
the tower and held at "arms length" by the cable arms.

http://www.qsl.net/w6old/images/party/stack-lo.jpeg shows the tower
fully retracted.  What you can't really see is how the cables form a
large coil at the bottom of the tower, but they are not attached to any
of the cable arms except at the very top.

http://www.qsl.net/w6old/images/party/kellems.jpeg shows exactly how
the cables are attached to the topmost cable arm so as not to be bent
or kinked by their own suspended weight.  Note how the cable arm loops
have been bent up to form hooks from which the Kellems grips are hung.

http://www.qsl.net/w6old/images/party/coaxarm.jpeg shows how the rings
on the other cable arms have been wrapped with plastic wire loom to
provide a smooth surface for the cables to slip through.

With this configuration, the tower can be safely lowered without worry
of cable damage.  Raising the tower is a different matter, because you
must take steps to ensure the cable hasn't become looped around
something; something that can be damaged or cause damage as the cable
goes back up the tower.

The precautionary step I have had 100% success with is to go out to the
tower and pull the cables out to the side, away from the base as far as
they will go.  This creates a big loop that I can ensure will not cause
any problems as the cable is taken up.  I then go to the base of the
tower, hit the Up switch and safely walk away, knowing there is nothing
in the way that can catch the cable as it is pulled up the tower.

I will admit I would be less sure of this process if I was raising the
tower remotely and had no way to ensure the cable was safely dressed
away from the tower.  I would want to check that it properly prepared
to go back up at least once each day and if there were children about
who could move the cable, I wouldn't want to raise it unless I had
checked the cable immediately prior to raising.

Then again, if there were children in the area, I would never even
consider remoted raising OR lowering the tower in the first place.

If you have any questions or if something doesn't make sense, please
let me know.  You are asking the same questions I did a couple years
ago and it took me a while to collect the answers.

73, Dick

At Mon, 28 Feb 2000 19:20:18 EST, N3SL@aol.com wrote:

>To the experts:
>
>I've got a USTower 72' motorized crankup here in northwest Iowa.  This is an
>80mph county, and with the house at the top of a rather large hill, there is
>rarely a calm day, and we have many many days with 30-40 mph sustained winds.
> When I received my tower last summer, I was rather unimpressed with the
>cable arms, and spent quite a bit of time trying to figure out how to do my
>cable runs.  Obviously, I didn't do well.  I've cut my rotor cable once,
>physically pulled both the rotor cable and Ameritron switch cables out of
>their connectors at least twice, etc.  The remote control of the tower is
>absolutely useless, as I cannot see the tower from the shack (XYL compliance
>issue), so cannot monitor cables.  Each of the mishaps has occurred when I
>"had no choice" but to lower the tower  remotely (either blizzard/driving
>downpour and/or in the dark).
>
>So, the question to the experts (those of you with trouble-free, successful
>cable installations) is:  How on Earth did you do it?
>
>Rather than taking up reflector bandwidth to my "personal problem," a reply
>straight to me is probably preferable.  Thanks in advance.
>
>Steve, N3SL

--
Dick Flanagan W6OLD CFII Minden, Nevada DM09db (South of Reno)
Visit http://www.cvrc.net/

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