You can *probably* get away with it. Our club does this
very thing every year at Field Day with five 50 ft R25 towers,
rotor, and home made 2L single band Quads for 20 and 15M.
The towers are pre-assembled on the ground, then raised
on step ladders to attach the Quads to the mast. As the
tower is raised, a couple of guys walk the bottom in to the
wooden base (see below), keeping the lift rope vertical.
A 20 ft 1-1/4 inch mast is inserted inside the 2 inch Quad
mast to support 80M dipoles at 70 ft, above the quads.
We use a trailor mounted 30 ft crankup tower with an arm
and pulleys attached at the top and bottom to make a (2:1?)
mechanical advantage block and tackle to lift the preassembled
towers in place. Guys are attached at the 40 ft level and
small mobile home screw anchors and pre-installed using
a giant rented power assist. Three threaded rods are placed
through a large piece of wood to provide a flat base which is
prepositioned and used to measure anchor spacing prior to
tower erection.
Tom N4KG
On Wed, 25 Jul 2001 w3svj@juno.com writes:
>
> How risky is it to hoist 60 feet of 25G from somewhere above the C
> of G? The club (Steel City ARC, W3KWH) is trying to get the ATV
> repeater receive antenna a bit higher above the tree line. The antenna
> represents about 1.5 sq ft of windload.
>
> The plan is to assemble it all on the ground and secure the top guys
> as well as tie down the hardline. Of course the earth end of the guys
> would secured and the tower plumbed when it is upright.
>
> The concern is, will the tower buckle under its own weight before it
> can be swung to the vertical?
>
> I have the "Big Book" but I can't find anything regarding this type
> of installation.
>
> Does the "fold over" installation equate to what we would be doing
> as far as stressing the tower near midpoint?
>
>
>
> 73 de Nate, W3SVJ, in Pittsburgh where it's not so smokey anymore.
>
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