[TowerTalk] Crankup tower installation tips.K0FF

[K0FF]

Allan, If you want to use the HDR300 rotor, you can order the tower
specially built for it. The bearings and rotor plate are offset from center.
If you use anything else, the standard tower is OK for them (Ham-M, Orion
etc). Check with the factory if you intend to use a Tailtwister. On some
models, you can't retract the tower properly with it because it sticks out
the side (like my 56' tower).

Also I suggest the MAST RAISING fixture. This is a great gadget that
installs temporarily at the tower top, and has a hand winch and cable on it.
With this it's a simple task to lower the mast down into the tower to
install antennas on top etc., and winch it back up. Then you slip the rotor
under it and let it back down a little. No pain, no strain. If you don't buy
one ready made, build one yourself.
The work platform is a little pricy but I find it makes tower work safer and
more comfortable. Much easier to get anything done standing on a flat
surface, and volunteers are easier to come by.

Coax arms are available that make the loops of coax stand out away from the
tower properly. By using flexible coax, the cable can be loop at each arm,
and won't coil up on the ground when the tower is lowered. I bring hardline
to the top of the first fixed section, then continue up through the loops
with RG389, which is quite flexible, and specs out better than 1/2 inch
Heliax. Put your coax relay box above the tower top on the mast, and you'll
just have a single coax to go a round the rotor. Make this piece a jumper,
so that it can easily be replaced later when it breaks. I use RG 389 to the
top coax arm, and fix it there so that it doesn't move when the mast turns,
and transfer to a flexible piece of RG8, to the relay box.

Get some SILICONE tape from the electrical supply house or Radio Shack. Wrap
all your coax joints with this first, for waterproofness, then top it off
with a layer or two of Scotch 33+, and finally hit it with a nice coating of
Krylon Clear enamel. A joint done in this manner will last forever.

Finally, the tower erection fixture is a real good idea. The way it attaches
is simple and elegant. A teenager erected my 89' tower with it (over a ton
before antennas and workplatform etc.), and used only one hand! Better yet
borrow one if you can, as you'll only use it once

Don't scrimp on the mast itself. I use the heavy Double reinforced Chrome
Molly Galvanized on the biggest towers, and reinforced galvanized steel on
the others. Single strength galvanized masts are available from Texas towers
that are quite strong. Also you can order high-carbon steel tubing from the
steel yard. It has a strength of 80,000 pounds per square inch, and is 24
feet long. This can be spray painted with liquid zinc, and I have one done
this way, and it's holding up fine, but Hot-Dipped galvanizing is superior.
Aluminum mast must be so thick to provide equivalent strength that the
weight advantage is lost. DO NOT USE WATER PIPE. Period.

Whatever mast you use, drill a hole in it just above where the rotor clamp
fits, and tap it for a 1/2 inch bolt. Also make sure there is a 2-1/4 inch
hole in the rotor plate, and saw out a notch on one side of it for the bolt
to pass through. On the top plate, and any intermediate bearing plates,
drill a hole large enough to pass a piece of steel wire with a thimble on
it. All this is for a winch cable to allow the mast to be raised and lowered
later. A little work now will save a nightmare up on the tower latter.

Touch up any raw edges with Cold Galvanizing spray, from the local welding
store, or larger hardware store.

Plan for 3 sets of ground rods, and install one set on each leg of the
tower. The tops of the ground rods must be buried. Coat the connections with
Contax or other electrical goo, and put an aluminum tin can over the joint
before burying it. Also you can partially fill the hole with ground up
charcoal before backfilling. Don't use flat copper strap for this. The tower
resonates at an audio frequency, and this vibration will cause metal fatigue
cracks in the strap. A braided copper will not do this. When I saw my first
one crack completely across, I switched back to braided for all outdoor use.

Finally, for safety, install an electrical disconnect box on the tower, in
the AC feedline before it gets to the motor control box. This is to remove
the source voltage if anything goes wrong, and to disconnect anytime you go
on the tower for anything. (an air-conditioner disconnect is fine and a good
one in a rainproof box is less than $10.00) When installing the disconnect,
also provide a drop cord for an electrical inline  outlet. Use a Wodhead or
other rubber covered outdoor unit. The last step is to remove the rubber
covered nut from the motorcontrol switch and install a metal cap over the
switch. Something like the cap from a spray paint can will do. Drill a hole
in it and slip it over the switch and put the nut back on. Now there is a
safety shroud around the switch so that it can't be bumped accidentally, or
a dropped object won't strike it.


Good DXing..

Geo>K0FF


-----Original Message-----
From: Allan Elstien <aelstien@wwa.com>
To: K0FF <K0FF@ARRL.NET>
Date: Monday, June 05, 2000 4:20 AM
Subject: Re: Tri-ex vs. US Towers


>Hi:
>
>Thanks for your e-mail. Based on what you have told me and my two ham
>friends locally who have 72' us towers I have decided to use them.
>
>I will purchase a 72' motorized heavy duty tower for my hf antenna and a
>38' 18 sq.ft load tower for satellite work.
>
>I would appreciate any insight into accessories. I believe I must order the
>limit switches as a separate item and probably want the heavy duty tilt
>fixture for the bigger tower.
>
>Thanks,
>
>73, Allan N9AT
>


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