I will send you an SASE for a copy of the information Steve. Sounds like
just what I need to put up a 4 EL DX Eng. 20M monobander (40' boom). I
had planned to use a tram type line attached to the mast about 5 feet
above where the beam will be bolted to the mast. This should compensate
for the distance between the tram line and the boom (lifting sling and
pulley distance). The mast is only 2" x .250 wall so I had also planned
to back guy the mast at the same point that the tram line is attached
thus preventing bending the mast from the weight of the antenna. What
material do you use for the tram line? I was thinking of 3/16" guy line,
but would you trust 1/8"?
73's de KN0Z Gary in Wyoming, MN
In a message dated 96-06-19 00:57:23 EDT, you write:
Does anyone know of any articles on using a trolley-cable system to put
>up a beam? We're thinking of using it for a 3-el 40 meter Yagi.
Hi, Zack --
You've got the right idea but the wrong technique. The "trolley" or
"railroad track" is where you have two ropes or cables and the antenna
sits on top of them. There's a lot of friction in this type of system
as well as antennas bouncing around, etc.
I use a tramming system for about 95% of my antenna installs. It'll
work with guyed towers, trees, etc. In a nutshell, you have a tram wire
attached to the top of the tower and the antenna is slung UNDER the tram
wire on an upsidedown pulley. The haul rope goes through a snatch block
at the bottom of the tower, up through a pulley at the point of tram
wire attachment and down to the load. When you pull the haul line, the
load on the pulley goes up the tramline. It takes about 1-2 hours to
rig it but only about 10 minutes to run the antenna up.
Another advantage is that you can run the antenna partially up the wire
and test it in the air. It only takes a couple of minutes to drop it
down and retune it and run it up again to verify your change. There
are a couple of subtleties such as tag line management and two-step
lifts that are also involved.
BTW, I have a copy of an article I wrote on antenna erection that
includes diagrams of the tram rigging system. If you're interested in a
copy, send me an SASE or your postal address.
73, Steve K7LXC