In a message dated 6/19/03 3:57:29 AM Pacific Daylight Time,
emailw8nf@yahoo.com writes:
> 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.
Install the rotator and mast, then use the mast for a ginpole. One 3 feet
or so long will be FB.
>
> 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.
How far are you from the street? Many cranes will go 100' with no
problem. It would be the easiest and safest way to do it. You could also
assemble the
antenna in the frontyard or so so that you don't have to assemble it in the
air.
>
> 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.
>
After rigging your haul line, just strap the boom to the tower. You can
tie off the haul line to take the weight. The boom will wiggle around a bit but
should work.
> Then, using a large stepladder, install the elements
> to the boom, while the boom is at the 12 foot height.
You can rent an orchard ladder that'll get you up to 12 feet or more.
They're the 3-legged ones you see in, well - orchards.
> Then, somehow shinny the beam up to the top of the
> tower, in the process getting it past the rotor.
Use the aforementioned mast/ginpole arrangement and it'll take you about
3 minutes to get it up there.
>
> So, it sounds like I'm going to have to climb this
> tower while it's nested.
>
Yep. You've got to attach everything up at the top sometime anyway.
The two ladder methods mentioned previously are the ones I use. Leaning a
ladder against a tubular crank-up is VERY dangerous. I have a small aluminum
plate bolted to the top step on my extension ladder. It has a vee notch in it
that'll mate up to a tree or pipe with no problem. Have someone spot you while
you climb it and tie it off to the tower and it'll work FB.
Also standing the ladder vertically against the tower works well too. I
usually tie the ladder off in two places - one that I can reach from the bottom
by standing on the motor drive and then up higher. Clove hitches are handy
for this maneuver.
> 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.
I wouldn't recommend this approach.
>
> 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.
>
Your ground crew will be holding onto the haul rope with the antenna on
the end so you won't have to do much of anything but get it into position and
throw the U-bolts in and tighten them up.
> 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.
Yep, use the mast as the ginpole and the rest will be strightforward.
>
> Thanks for tolerating me as I "do" my very first tower
> install...
>
Sure. We all started out not knowing anything - hi.
Good luck and congratulations on your new tower and antenna system.
Cheers,
Steve K7LXC
TOWER TECH
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