I've had a three-section crank-up tower (it used to be called the LM-354)
that's 54 feet tall when fully extended. For a long time, I used it in a
permanent fully-extended manner, with phased ten meter yagis at the top and
half-way up. Now, it will have a triband yagi and a two-element 40 yagi on
it, above the thrust bearing, and I wish to keep it at least semi-nested
between contests to avoid storm damage. What is the recommended way of
bringing down two the coax feedlines and the rotator cable for a tower that
will go up and down fairly regularly? I'm going to use the three original
"stand-offs" to keep the coax and the rotator cable hanging vertically as
these three standoffs are positioned such that they nest properly when the
tower is down. Is it okay simply to hang the feedlines and the rotator
cable down through the top standoff, which seems to rotate around as the
rotator moves the mast, and simply let the coax and cable drop down
vertically? In this case, there would be no traditional rotator loop. That
configuration has worked okayrecently with only the small 40 meter yagi on
the top.
Another possibility would be to form a five or ten foot "rotator loop" with
the feedlines and rotator cable and then route them back up onto the top
standoff and down vertically through the other two. In this way, the system
would not require that top standoff to move around on its tower leg as the
mast and antennas rotate. Not sure if I described this in a clear way. If I
were sure that the top standoff would move around on its tower leg, that
would work, but if the top standoff got stuck and didn't move, then the
feedlines and rotator cable could get stretched and damaged. For some
reason, I haven't seen anything on this, or have forgotten. Any
recommendations?
Thanks in advance, and all the best at the Christmas and other holiday
breaks and new year.
73, Jim George N3BB
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