Hi All-
Am new to this forum, so please excuse my ignorance on posting messages. I sent
the following query to the Antenna forum last week but never received a reply.
Maybe it didn't get through, or maybe no one had an answer, or no one felt it
was worth commenting on, but in either case this seems to be a much more active
forum, and there seems to be as much discussion about antennas as there is about
towers. I've been QRT longer than most people have been alive, but am now
planning on getting back on the air in the near future. All I need is a new QTH
without deed restrictions, new equipment and a tower with antennas. Minor
details.
Anyway, got to thinking, which is usually where I get into trouble. On the
subject of support guys for yagi/quad booms, I've only seen two types over the
years. For lateral support, guys are usually run from near the end of the boom
to the ends of a crossbar which is installed on the boom near the mast, or
installed on the mast itself. For vertical support, wires are run from the ends
to the boom to the mast at some point above the boom. This is potentially six
lengths of wire, and one area that is still not addressed is that of torque on
the boom, but which can occur in varying degrees. What I was thinking of was
this, and it's kind of hard to describe: For discussion purposes, all
dimensions are theoretical and not important.
Consider the diameter of the boom to be 0", and envision the boom as viewed from
overhead, represented as a single vertical line. You would install crossbars
near each end of the boom that are approximately 2' long. You then install a
crossbar on the mast, approximately 6' long and mounted about 3' above the boom.
Run a guy wire from the left end of the top crossbar to the right end of the
mast mounted crossbar, then another line from this point to the left end of the
bottom crossbar. Repeat the process for the other side, i.e. from the right end
of the top crossbar to the left end of the mast mounted crossbar, and then
another line to the right end of the bottom crossbar. In this configuration,
you've used four wires to support the boom laterally, vertically and to prevent
torque. Chafe where the wires cross could be handled by any of several
methods. Does this make any sense? Any comments would be most appreciated.
Regards,
Bob Gates, KG7KW
ex K7INE and PJ9KW
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