Greetings,
I am putting up 100’ of Rohn 45 and plan to put a Force 12 EF-420/240 (2
element 40m interlaced with 4 element 20m yagi, 30’ boom length, 22’ longest
element, 23.3’ turning radius, wind area 8.4 sq ft) under either a hy-gain
LJ-153BA (15m monoband yagi, 12’ boom length, 25’ longest element, 14.25’
turning radius, wind area 3.0 sq ft) or a hy-gain LJ-155CA (15m/12m yagi, 26’
boom length, 25’ longest element, 17.5’ turning radius, wind area 5.2 sq ft).
Due to the use of the long booms and elements, I am concerned with the torque
that this stack (loaded with 3/4”-1” max of ice) will induce on the tower –
fearing a tower twisting failure mechanism.
As a countermeasure, I plan to use the TA45 Torque Arm Stabilizer Assembly at
the top level of guy wires, and perhaps the top two levels of guy wires. My
first question is, “Does a TA45 at the second (from the top) level of guy wires
provide any substantial level of protection from a tower twisting failure
mechanism standpoint?”
The second question that I have is related to guy tensions. For a 100’ Rohn 45
tower, the top set of guys are 1/4” EHS tensioned at 665 lbs, and the middle
and bottom sets of guys are 3/16” EHS tensioned at 399 lbs. Using the TA45
there will be six guys at that level, two guys per guy point. Does each of the
six 1/4” EHS guys still get tensioned to 665 lbs? I suspect the answer is yes.
It will double the vertical load on the tower due to twice the number of guys
at that level, but I doubt that is a significant percentage of the vertical
weight that a Rohn 45 can handle.
Thanks in advance for your advice. It is much appreciated.
73,
Doug – KG5OA
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