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Re: [TowerTalk] How to deal with Coax on a Crankup Tower

To: 'Larry Loen' <>,
Subject: Re: [TowerTalk] How to deal with Coax on a Crankup Tower
From: Grant Saviers <>
Date: Mon, 19 Nov 2012 08:58:14 -0800
List-post: <">>
Chris, KF7P makes arms with free sliding loops and also with hoops that the coax is tied to.


The hoop design keeps the coax from kinking, keeps it on the tower, although enough slack is needed to still have an "upward" exit loop for when the tower is fully extended. I'd guess about 5' more coax is needed for every hoop vs loop standoff, if that loss is a concern.

My cable bundle per tower (2x HDX589) was 3 x 9913F7 or Buryflex (much better stuff than 9913) plus rotator plus ethernet plus a 4 conductor control cable for tower mounted gadgets. The hoop design worked fine on one tower, but it wasn't easy for me to get the loops the right length between hoops. On the other tower, they just wouldn't work - kept getting snagged going up. Bundled cables seem to get a mind of their own about twist and residual bends. Mine were carefully pulled without any twist, then 3M taped every 18" or so. One tower's bundle was well behaved on the hoops, the other wasn't. One of the rotator cables was noticeably stiffer and with different coax that made the difference, I think. Another risk with hoops might be trying to lower the tower when the wind is blowing the coax around and it snags.

Steve K7LXC took one look at the hoops and said "that's not going to work." Oh well, many trials with hoops had me talking to Chris and he made it right by exchanging the hoops for loops and they work great on both towers. I measured the offsets and extensions for the 589 as he had not made them for that tower in its current UST revision. Now they are a thing of beauty :-) .

Pre twisting the bundle is an interesting idea to keep it in a container. I chose to use the mariners trick to flake heavy lines into a figure 8 as the tower descends. Each half twist reverses the prior half twist. One tower's concrete base grew large enough (another story) that the coax flakes on it and the other is surrounded by grass so it's not messy. Having a clean work area around the base is a really good idea - gravel, grass, pavers, etc. It is small cost/effort considering what is otherwise invested. Of course, I need to attend 100% the tower lowering, but I wouldn't ever think of lowering these towers remotely.

Grant K71W

On 11/19/2012 7:36 AM, Dick Dievendorff wrote:
At my last installations I chose option 1), and as I lowered the tower, I
guided the coax bundle into a circle on the ground. I added an angular
support to the topmost stand-off arm so that the weight of the whole bundle
was better supported.  I had 6 RG-213 coax cables, rotator, and a control
line for 80/75 relays on a dipole.  The coax bundle was taped together about
every two feet.

I saw a really neat installation at N6EK a few years back.  Bob had a large
washtub inverted on the ground.  He had applied the right twists to the
cable so that it coiled rather naturally around the washtub all by itself
when the tower was lowered.

73 de Dick, K6KR

-----Original Message-----
From: TowerTalk [] On Behalf Of Larry
Sent: Monday, November 19, 2012 7:22 AM
Subject: [TowerTalk] How to deal with Coax on a Crankup Tower

Slowly, but surely, my tower project is making progress.

Got a lot in place or will shortly finish.  Tower is mounted, grounding in
place, A/C power.  It's getting real.

Now it is time to consider a homely little problem I have given no
significant thought to:  Routing the coax up and down the tower as I crank
it up and down.

The tower's manual gives me no explanation on the coax stand-off arms that
come with it.  It states helpfully that when I install them correctly, they
will line up top to bottom.  That was OK and expected.  What is not obvious
is exactly how, exactly, the coax ought to "travel" on the tower.

The standoff arms themselves seem to consist of an open loop that has room
for several coax to be in them.  Good as far as it goes.  But, it seems to
admit to two designs.

1.  Let the coax freely fall the whole 60 to 70 feet (this will vary based
on the three coaxes I will be running up the tower).  The cable would be
"guided" by the standoffs, at least as far as the tower, proper goes.

2.  Fasten, in some manner, the coax to each stand off.  There would be a
modest amount of slack when the tower was fully extended and more when it
was not.

At the W0IBM club station, which had basically the same tower, the second
option was chosen.  It would be using 9913 F for my runs, so that the coax
would be largely in the air.  As at W0IBM, it would simply form a graceful
and natural loop between each standoff when the coax descended (I'm pretty
sure the W0IBM tower used RG8 or something flexible -- no 9913F back then).
I could also attach the DC control wires for the rotor to the coax as well
(I presume).

If I chose the first option, which the design of the stand offs kind of
superficially invites, the coax would have to "pool" at the bottom of the
tower, and it would do so in a place that looks rather unfriendly for the

It seems "obvious" to me that the second should be chosen, and yet I don't
remember seeing much discussion about this.  Or, details about how to attach

Assuming the W0IBM solution is the right one (it would also help frustrate
the local copper thieves, too), how do I attach the coax to each stand off
and do so in a way that helps fight off the Arizona sun, which does things
like bleach "caution" tape in about a month's time?

Larry Wo0Z

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