[TowerTalk] Telescoping Tower Coax Routing

[Dick Flanagan W6OLD]

>From: Teddyer@aol.com
>
>What is the preferred way to route and support the coax and rotator
>cables on
>a telescoping tower?  I am installing a US Tower TMM-433SS (33 ft)
>tower.
>
>Thanks,  Ted (WB2ACC)


>From: KJ6Y@aol.com
>
>US Tower sells standoff arms to support the cables and keep the away
>from the
>tower.  Coax arms are list as CX and the the number you'll need.  One
>for each
>section, ie, 4 section tower would use the CX-4
>
>Skip, KJ6Y

You will quickly find there are two near-religious camps on this issue.
:)

Just about everyone suggests using the manufacturer's standoff arms.
The difference comes in regarding whether to physically support the
cables at each arm or to support them only at the very top and allow
them to loosely slip through the arms.

First, understand that coax is not very heavy.  A hundred feet of
quality RG213 will weigh less than ten pounds.

Second, understand that coax is pretty strong stuff.  It can easily
hold its own weight when hung from the top of the highest amateur radio
tower (assuming the usual 200 foot maximum tower height).

Third, understand that you want to avoid any sharp bends or kinks in
your coax.  This is especially true of air or foam dilectric cable.

I am of the religious persuasion of allowing the coax to freely slip
through the  coax standoffs while being secured only at the very top of
the tower.

The key to this technique is to properly secure the coax (and other
cables) at the top support so as to not cause any kinks or other
small-radius bends.  This is where Kellems grips are ideal.  These are
the cable grips that looks like children's Chinese finger puzzles that
slip over the outside of the cable and grip tighter as tension is
increased.  I use Kellems #022-16-003 which fit cables from 0.35" to
0.44", ideal for RG213-type cable.  They are available at most large
electrical supply outlets, although you may have to special order these
smaller sizes.

By allowing the coax to slip though all of the lower supports, you will
wind up with a large loose coil of cable at the base of the tower when
it is lowered.  The only caution here is that when you again raise the
tower, you have to be careful the cable doesn't catch on anything at
the base of the tower as it goes back up again.

Some folks argue in favor of securing the cables at each support,
because it prevents the large coil at the base of the tower.  Instead,
you wind up with a series of cable loops hanging from each support when
the tower is lowered.  Personally, I worry about the loops catching on
the supports when the tower is raised and I also worry about the sharp
bend radii when the secured cable is allowed to hang in its loops at
each support.

Your mileage (and other opinions) may vary.  :)

Good luck with whichever approach you choose.

73, Dick

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



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