Dave,
With the usual disclaimers to follow the manufacturer's recommendations:
Sounds like a U.S. Tower tubular, so I can tell you what I do with my
MA-770MDP (the 72)-footer. I climb it with a ladder. I'm aware of two
methods for doing this:
1) Two different professional installers told me they lean an aluminum
extension ladder against the tower, have one or more persons hold it at the
bottom, then climb to the top of the ladder and attach the top rung to the
tower with rope, straps, etc. Once the top of the ladder is secured to the
tower, it's relatively safe to climb -- provided you follow general ladder
safety rules. This process can be made safer by using a tree attachment.
This is an adjustable bracket that attaches to the top of the ladder and
normally wraps around a tree trunk. This will help to keep the top of the
ladder from slipping off the tower (but you still need your ground crew to
hold the ladder steady.) I have a picture of a professional installer
carrying(!) a TH-7 up a ladder to the top of a U.S. Tower tubular. I
wouldn't recommend this method. I was told a big gust of wind came up and
the guy barely managed to hang on to the ladder.
2) I use a different method on my tower because the ground slopes rapidly
away from the base, making it difficult to plant the ladder securely on flat
ground. Also, the above method cannot be done by one person. I secure the
ladder to the tower in a vertical position, flush against the tower. I place
the feet of the ladder on the concrete slab and walk the ladder up, raise
the ladder extension up about 6 feet, then secure the bottom part of the
ladder, as high as I can reach, with a series of heavy rubber bungee cords
and cargo straps. Then I extend the ladder the rest of the way to the top of
the tower. I strap on my climbing harness, put the lanyard around the tower
and ladder, secure the fall-arrest lanyard to the tower (or the ladder if no
suitable part of the tower is available) and begin climbing the ladder. This
is a lot like climbing a Rohn tower. Depending on your ladder and shoes,
there may not be a whole lot of room for your feet, so you have to be very
careful with foot placement. I secure the ladder with additional cargo
straps as I climb, always standing on the secured portion of the ladder and
reaching as high over my head as I can to attach additional cargo straps. It
usually takes about 8-10 heavy-duty ratcheting straps to do the job. By the
time I get to the top of the ladder, it's securely fastened to the tower. Do
not attempt this method without proper climbing gear used properly.
Since my tower tilts over (and rotates), I originally mounted a TH-7 by
tilting the tower and getting about six friends to help muscle the TH-7 to a
nearly vertical position so that it could be attached to the top of the
tower (which could not be tilted all the way horizontal due to the TH-7 boom
length -- it had to be about ten feet off the ground.) A big guy on a big
step ladder was needed to secure the beam to the mast.
Since then, I have removed the TH-7 and replaced it with a 4-el 20m
monobander with a 30-foot boom. It took two people, myself and a friend, to
do this. I used method #2 to climb the tower and attach a boom-to-mast
bracket above the TH-7 on the mast. I attached a short piece of mast (heavy
steel pipe) horizontally to the bracket and attached a pulley to the short
piece of mast. I pulled a rope through the pulley, attached one end to a
rope sling on the TH-7, and dropped the other end to the ground, where my
friend pulled it taut and secured it. Then detached the TH-7 from the mast
(strut cables, too), and went down the tower and helped my friend lower the
beam to the ground. The 20m monobander was raised in reverse fashion. Both
beams are quite heavy, so in retrospect we should have used a pulley at the
bottom of the tower so the rope could have been pulled horizontally with
additional mechanical advantage. Once the monobander was raised and the rope
secured, I scurried to the top of the tower and attached the beam to the
mast (I had to lift the beam onto the bracket, but that wasn't too hard.)
If there isn't enough room in your yard to lay the beam flat and hoist it up
the tower, then you might be able to assemble the elements to the boom after
attaching the boom to the mast. This would require a swivel-mount
boom-to-mast bracket. I think PVRC developed something like that.
73, Dick WC1M
> -----Original Message-----
> From: Dave Haupt [mailto:emailw8nf@yahoo.com]
> Sent: Wednesday, June 18, 2003 3:08 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Do I need to climb my tubular tower?
>
>
> Hi all,
>
> Looks like I'm going to have a 50 foot crank-up
> tubular tower. 23 feet tall when nested.
> Self-supporting in 4 yards of concrete, probably.
>
> I'll be putting a tribander on it. The rotor will
> mount at the top of the tower - this is not a rotating
> tower.
>
> How do I get the tribander up there? The yard in
> which the tower is planted is far too small for the
> antenna to be fully assembled at ground level.
>
> Until I get up to 12 feet off the ground, there is
> house, shed, fence, or tree within 10 feet in every
> direction, except for a 30 degree arc where the
> distance is about 20 feet. Because of zero lot lines
> and houses within a few feet on each side, there is no
> way to get a boom truck back there.
>
> Assuming it's a triband Yagi, I think the approach is
> to mount the boom at the 12 foot height level. This
> isn't trivial; the tower is 6" diameter at that
> height. So I think it will involve a homemade
> temporary bracket of some sort, possibly made of wood
> and employing hose clamps somehow. Haven't sorted out
> that detail yet, but I think it's possible.
>
> Then, using a large stepladder, install the elements
> to the boom, while the boom is at the 12 foot height.
>
> Then, somehow shinny the beam up to the top of the
> tower, in the process getting it past the rotor.
>
> So, it sounds like I'm going to have to climb this
> tower while it's nested.
>
> Has anybody done this before? I can imagine adding
> various brackets, again probably wood bits clamped to
> the tower, for foot rests, to enable climbing it. I'd
> have to consider very carefully how to attach the
> climbing belt - I won't sacrifice safety. If the
> method of climbing is slow, that's OK, as I don't plan
> to do it much.
>
> Once the beam's shinnied up to just under the rotor,
> have to figure some cable/chain, etc configuration so
> that if I lose hold of it while moving it to a
> position above the rotor, it can't fall.
>
> The whole thing seems more possible because the
> "height" work is only at 23 feet, not 50, but it's
> clearly not without risk.
>
> A possible alternative is to attach a pulley to the
> top and haul the beam up that way. I still have to
> get myself up there to do the attaching, which will
> require again either climing the thing or finding a
> ladder tall enough, which is not a trivial task in
> itself.
>
> Thoughts? Alternatives? BTDT?
>
> Thanks for tolerating me as I "do" my very first tower install...
>
> 73,
>
> Dave W8NF
>
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