With all due respect for Chas' experience, I have three antennas hung with
Parachute cord. One has been up about 8 years, one about 5 years and the last
one has hung from my tower only 2 years. I also have a halyard hung about 60'
up in a tree that I pull antennas up and test them that has been up 8 years
like the first dipole I hung when I moved back home. I bought a 1000' spool in
1991 at the HossTraders Hamfest in NH and still have about half. I also use
some of the good Black Stuff to guy verticals.
The only failure I have ever had was when I ran over with the lawn mower the
end of one of dipole ends which had fallen into the grass. (oooops) . It
wrapped itself around the blade bearing and I had to cut it out. All it did
was shorten the end so I will have to tie a piece on when I want to lower that
end of the dipole (or I could just let it fall) .
I think the key is to buy quality cord. I have seen some really poor stuff in
the $ stores but if you go to a good Outdoor store that serves climbers I think
you can find some that is worth buying.
Clint - W5CPT
----- Original Message -----
From: chas
To: Jim Brown
Sent: Monday, June 22, 2009 1:12 PM
Subject: Re: [TowerTalk] Phillystran and Pulleys
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
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