[TowerTalk] Phillystran and Pulleys

[chas]

Jim Brown wrote:
> 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


yeah!!  NEVER use parachute cord!!!  that stuff rots thru in a year 
here in Houston.  I only use the double braided polyester 3/16" or a 
size larger maybe.  the 700# test stuff.

I have kept a mast up for 5 yrs now with this stuff and it still is 
perfectly strong.

geee, I thought everyone knew to not buy chute or riser cord for 
anything but boot laces or some such.

chas
k5dam, houston, TX