On 10/13/2014 10:12 AM, Ralph Mowery wrote:
"Lostgallifreyan" wrote in message
. ..
"Ralph Mowery" wrote in
:

Looking at a chart in an old ARRL antenna handbook gives a rough
estiment of a length of 500 feet and a tension of 400 pounds a wire of
around 12 to 14 gauge will drop about 10 feet if Idid it right.


That's useful. Thanks. Did they say what metal it was? I'm guessign hard
drawn copper but if not it may be harder to adjust reckoning for something
else.

They gave two types. Hard drawn copper and copper coated steel. The only
differance would be the weight of the wire and how much tension you can put
on the wire before reaching the breaking point. The type of wire does not
matter, just the weight and how much tension you can put on it before it
breaks. Really how much tension you can put on the wire with a large safety
factor. Probaly less than half its actual breaking tension. I know that
Rohn towers specifies about 10 % for their guy cables. That is for the 4000
breaking of 3/16 cable they recommend 400 pounds of tension on the guy
cables.


That is STATIC tension - that is, when no wind is blowing. Tension
increases significantly when there is a wind. Rohn tower specs are
designed to withstand winds of 85mph, IIRC (I last did commercial tower
work in 1972 or so, so I don't remember the exact specs). At that wind
they have maybe a 50% safety margin. Still significant for new cable,
but when your guys are 25 years old, the tower should still withstand
that wind.

And yes, some of the towers I put up over 40 years ago are still
standing. But I'm sure they've had some maintenance since that time.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================