If ones antenna requirements are modest, and if one has sufficient clear
space around the tower and antenna, it is not difficult to hinge a self
supporting tower so it can be raised and lowered fairly easily for
antenna changes and maintenance.
I recently installed an aluminum 60' tower. The light weight of
aluminum is favorable for how I raise and lower it. I designed hinges
for a gin pole (a support structure that connects to the tower with a
cable and maintains about a 70 degree angle between the tower and the
gin pole) as part of the base for the tower. The gin pole is two
twenty foot 2 X 6s, with hinges made of 1/4" steel and spaced 30" apart
at the base. The 2X6s are X-braced with angle iron and they are about 1
1/2" apart at the top, spaced by a smooth piece of pipe on a bolt at the
top.
At present, I use two vehicles to raise or lower the tower. One pulls a
cable attached to the top of the gin pole, from which the other cable
runs to the tower at about the 20' point to the leg opposite the tower
hinges. That vehicle and cables are to raise and lower the tower. The
main purpose of the other vehicle, which is tied to the hinge side of
the tower at about the 20' point, is to snub the tower as it nears its
vertical position, as the combined weight of the tower, antennas, gin
pole, and cables tends to drive it the last few degrees upward harder
than I wish. The other purpose of the second vehicle is to start the
tower down, as all that weight requires a fair amount of force to start
the tower over. This whole arrangement works without straining my back!
The snubber vehicle is positioned about 50' from the tower and
sufficiently to one side that the tower doesn't come down on it.
The vehicle that raises or lowers the tower is about 50' from the tower
base when the tower is down and a bit less than 70' from the base when
the tower is up.
The cable I'm using to raise and lower the tower and the cable from the
gin pole to the tower each sustains a maximum load a bit less than 800
#. At present, I'm using 3/4" nylon rope rated for over 11,000#, but
will change to steel cables soon. In addition, I may install supports
for winches so I don't have to use vehicles. That will be a little more
convenient and require less space for operating, though I have plenty of
space. I intend to be very particular about the winch, though. I won't
use any winch for raising and lowering the tower that can free run if
the operator accidentally lets go of the handle. I consider that
extremely dangerous to both the operator and the equipment!
This is my alternative to climbing. I experiment with antennas a lot,
so I need frequent access, and I'm not fond of climbing, especially
without another person present to act as my safety officer. This scheme
works very smoothly and easily, for antennas up to typical 3 element
tri-banders. Anything larger would still require a cherry picker to
reach the attachment of the boom to the mast. I'm not fond of extra
tall ladders, either!
However, it occurs to me that, with proper support under the tower when
it is lowered, an extension ladder could be placed against it to reach
the boom-mast junction. Hmmmmm? Of course there is no great reason to
put a 40 meter beam at 60'. Not when one has space for good vertical
arrays for the low bands, with enough copper wire salvaged from a power
transformer for the radials needed.
This suits me. Hope the ideas help others.
73 de WOØW
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