K7LXC at aol.com
K7LXC at aol.com
Wed Jun 19 11:19:34 EDT 1996
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
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
TOWER TECH -- professional tower supplies and services for amateurs
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