In a message dated 4/6/2007 3:24:30 P.M. Pacific Daylight Time,
towertalk-request@contesting.com writes:
> Also be sure to include the wind area of your feedlines--they add up
quickly! For example, for RG-8/LMR-400 (diameter 0.405"), 87 ft along the
tower leg gives you another 87 ft x 0.405 in x 1 ft/12 in = 2.94 ft^2. Two
of these lengths gives you 5.87 ft^2, etc. (These numbers don't include the
factor for round members, but Rohn specs include this factor in their "round
member" ratings.)
Well, yes and no. Commercial towers typically have each feedline going
down the middle of the face down a cable ladder so it and all of its brethren
are totally exposed to the wind. OTOH hams don't use that technique and run
the cables down a leg or two. So instead of having to add up all of the
exposed cables, ham cables make the leg(s) slightly larger - and much less of
a
factor than the commercial towers and Rohn spec.
Cheers,
Steve K7LXC
TOWER TECH
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