[TowerTalk] Questions about Rohn TA45 Torque Arm Stabilizer Assembly

[Doug Howard]

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