In a message dated 97-01-09 11:46:34 EST, you write:
>If there is any question about the strength of the top support,
>I'd recommend using a temporary back guy, from the top support
>to a solid attachment on the ground, running 180 degrees around the
>tower from the tramline bottom.
An elegant alternative to a separate backguy is to use one continuous
cable that passes through a pulley/sheave at the mast. That way, the forces
are roughly equalized at the mast and you only have to deal with one cable.
Either method does work and is highly recommended for medium sized projects
and up.
>
>Tramlines are cool. It takes all day to set them up properly and
>another to take them down. But when they work right, I've been
>able to install large antennas with no more ground crew than the XYL.
>
Two other nifty facets are 1) you can raise the antenna part way up the
tramline while dangling a temporary feedline to it for initial testing. And
2) the antenna can be lowered quickly for tuning adjustments or installation
problems and raised again in a matter of minutes. This would include having
a tag line hung up on the antenna, etc. You can lower it and raise it back
up again in 5-10 minutes. Like any similar job, it's the rigging that takes
most of the time.
Again, if anyone is interested in an illustrated article on installing
yagis including tram systems, an SASE to TOWER TECH, Box 572, Woodinville,
WA, 98072, will get you a free copy. BTW, Tom Schiller, N6BT and Force 12,
has written a book called "Array Of Light" and he has a chapter on installing
yagis. His methods are sell suited for limited space projects where you may
not have room for a tram line (sneaking the beam around guy wires, etc.).
It's $10.00 from Force 12 and an interesting read of Tom's extensive tower
and antenna knowledge.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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