Ok, heres something I dont get. Star guy setups.... with 6 guy wires. The
idea is to reduce tower twist. I can readily see that vs a standard 3 guy
wire ...per level setup.
Then we have folks with a rotating tower assy, whose guy wires essentially
allow for unlimited tower twist. The only thing I can see limiting the
twist is either the rotor at the bottom of the rotating tower,
and / or the bearings at each rotating guy ring assy. The folks with
rotating towers typ load em up with yagis from top to bottom. All yagis are
mounted to the same tower face, so you now have a TQ offset from
boom to exact center of tower... which just makes any TQ issues worse.
It appears that a rotating tower assy is one giant, 100-200 ft tall
driveshaft. How much twist do you rotating tower owners see in a 40-75 mph
windstorm ? (and tower sitting there, not being rotated at the time).
Ok, what if no wind at all, nice sunny day, and you rotate tower say 300 degs.
Do you see any twist when rotor initially engaged ? IE: base of tower is
turning, but very top of tower has not started to rotate..yet.
What am I missing here ? Rotating towers vs star guys is from one extreme
to the other. One would think with a 100 ft rotating tower...and esp with a
200 ft rotating tower, it would twist like a pretzel ?
When I worked for the telco, the odd site would have star guys, if a guyed
tower was used, and large diameter microwave dishes used. Same deal, 6 guy
wires used, with star guy assy just below the dish.
In some cases, a square tower was used, with 8 guys, 2 for each of the 4 x
faces...and 4 x guy anchors on the ground, 90 deg apart. I can understand
the telco application, the dishes had their side built up, and
they have an extremely narrow main lobe. With the sides of the dish built up,
there is no side lobes. For amateur HF, its not an issue. But tower twist
is an issue. Or is it a non issue ? Obviously 65G will twist less than
25 G. For this discussion, lets use 45 or 55G as tower used in a typ
rotating setup.
Jim VE7RF
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