[TowerTalk] Weight on ends of a OCF diploe

[Jim Brown]

On Thu,8/11/2016 9:14 AM, Chuck Gooden wrote:
> My question is how much weight will I need at the ends to allow for 
> wind movement of the trees? 

It depends on how much the trees sway, how high the antenna is, how much 
wind, and the weight of the feedline. I'm using about 90# on my two 
80/40 fan dipoles at about 140 ft, fed with about 160-180 ft of RG11. 
Same for a 160M tee vertical, with the top at about 100 ft, a reflector 
for one of the 80M dipoles at about 120 ft, and a pair of 30M dipoles at 
about 100 ft. They are hung between redwoods (and one Douglas Fir), with 
pulleys on both ends. One support rope is tied off, the other has the 
pulley. Because I'm in a dense redwood forest, I guestimate that my wind 
never gets worse than about 75 mph. No failures in 10 years. The 
antennas are either #10 THHN or #9 hard drawn copper, and I'm using the 
5/16-in antenna rope sold by several ham vendors, including DX Eng and HRO.

When I've had these antennas down for maintenance, I HAVE seen some 
damage to the support ropes on the Tee vertical caused by wear on the 
outer covering at the pulleys. None of these failed, but that failure 
exposes the inner part of the rope which is structural to UV, so it 
would eventually fail. So when this happens, I've replaced it.

As you might guess, the quality of the pulleys is critical. My favorite 
is this one, made by CMI. The two sides of the pulley rotate with 
respect to each other, making it easy to put the rope into it without 
have to pass one end through the pulley.

https://www.cmi-gear.com/collections/frontpage-2-service-line-pulleys/products/rp115

73, Jim K9YC