[TowerTalk] Phillystran and Pulleys

[donovanf at starpower.net]

Jim,

Phillystran isn't intended for that application, so I doubt it would be a good choice.   Perhaps someone has specific experience in this application.

Perhaps your best choice would be something like 5/16" dacron, but not the braided variety.   I'm sure you will goet some good feedback from others on good long lived ropes where motion over pulleys is an issue.  Small diameter pulleys are serious detriment to rope life, I use 3 and 4 inch shieve diameters only.

73
Frank
W3LPL

---- Original message ----
>Date: Mon, 22 Jun 2009 09:57:42 -0700
>From: "Jim Brown" <jim at audiosystemsgroup.com>  
>Subject: [TowerTalk] Phillystran and Pulleys  
>To: "Tower Talk List" <towertalk at contesting.com>
>
>Crew,
>
>I've got some of the smaller 1,200 lb test Phillystran that I bought 
>years ago for a wire antenna project that didn't happen. It's too 
>small for the 120 ft Rohn 25 that I'm preparing to install, but I'm 
>wondering if it would work on my high dipoles that are up 110 ft in 
>redwoods? 
>
>The existing antennas, 80/40 fans fed with 150 ft of RG11, are held 
>up by ropes (the "good" stuff that DX Eng and some other ham vendors 
>sell) through good pulleys, but the black UV sheath of these ropes 
>gradually abraid from friction as the trees sway, and eventually they 
>fail. A 5/16-inch rope holding up my 160M Tee vertical failed after 
>two years -- the sheath wore through completely, exposing the inner 
>white material. Luckily I discovered it before it rotted in the sun 
>and dropped, and was able splice in a new rope and pull it through. 
>
>I'm not worried about the pulling strength, which is certainly 
>adequate, but I am concerned as to whether the Phillystran would 
>stand up to continuous flexing at the pulleys as the trees sway in a 
>storm. Each antenna is counterweighted (about 100#) at one end, 
>pulleys at both ends. 
>
>Thoughts? Experience?  
>
>73,
>
>Jim K9YC
>
>
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