Holy Cow, that is one massive antenna!
Doug, since you have no prior experience erecting towers, I urge you to hire
an experienced professional tower rigger to help you with this project. If
you can't erect the towers with a crane, as now required by the
manufacturer, you will have to carry out several steps that are potentially
extremely dangerous. A pro is much more likely to know what to do and what
not to do, and has a much better chance of doing the project safely than you
do. This antenna is not worth your life.
Here are some specific comments:
1. I don't know the structural characteristics of the towers (and neither do
you), but I agree that no matter how strong the sections, 1" base bolts call
for temporary guys. But I wouldn't fool around with ropes -- use steel guys
properly attached to the tower/anchors and properly tensioned. The load on
the tower won't be just the wind and your body weight. Tremendous force will
be put on the tower, especially the top section, when you winch those 800 lb
sections. I sure wouldn't want to be the fellow at the top while that's
going on unless the sections below me were properly guyed (and even then I
guarantee the "pucker factor" will be significant -- it sure was for me when
I was on the tower receiving my puny 10-foot Rohn 55 sections at 100 lb
each.)
2. If you have to fabricate a gin pole, get the design checked out by an
engineer. Failure of that component could be disastrous or even fatal.
4. Think about how you'll move the 20'+ gin pole up 20' to the top of the
tower to hoist the next section. Even if it's made of Rohn 25, it'll be very
heavy. At a minimum, you'll need a pulley and rope system to haul the gin
pole up even with the top of the section you just installed. Assuming the
design includes a clamp system that allows you to slide the gin pole up
above the just-installed section, it's unlikely you'll be able to lift the
gin pole from the bottom while you're on the tower. Perhaps you'll have to
use a separate heavy-duty gin pole to extend the big gin pole with the
winch.
5. How are you going to raise the antenna? The manufacturer's site says that
in the guyed configuration the mast tilts over for antenna maintenance. Is
that the model you have? If so how is the mast tilted? Is there a separate
winch pole/fixture? It will certainly have to be very heavy duty to handle a
2100 lb antenna with a 70' boom and 100'+ elements on a 100' mast.
Just some thoughts.
73, Dick WC1M
-----Original Message-----
From: Doug Ronald [mailto:doug@dougronald.com]
Sent: Tuesday, January 17, 2012 9:04 PM
To: TowerTalk@contesting.com
Subject: [TowerTalk] Safety of unguyed tower
> I have seen heavy duty gin poles capable of lifting heavy tower
> sections,
but I have never found a place that sold them.
>Where are they commercially available?
That was my first problem - the vendor no longer supplies them. Commercial
TV tower suppliers have them, but the cost is out-of-sight. I was on my own
to fabricate the gin pole.
>Telex / Hy-Gain made a dual tower system model T-3002 that sounds similar.
>The mast was in-between the towers and the rotator was installed at the
base
>and there were guy wires at the top of the tower. Without knowing
specifics,
>it's hard to determine if it's safe to install up to the guy point or
>if
temporary
>guys are needed.
That is the product I have, a T-3002FA now from the company that bought-out
Telex, U S Antenna Products. The antenna itself is the LP1005AA Log
Periodic.
-Doug
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