Using the nomograph in the ARRL Antenna Book,
which only goes up to a SPAN of 1000 feet
(and only after an hour did I see that "SPAN" is
one HALF the distance between end points),
I can't find any wire that can survive that SPAN,
when you've only got 50 feet for sag.
I've got a distance of 2400 feet for the long wire
between two 70 foot high bluffs on opposite sides
of a saltwater inlet that is shoaled and un-navigable.
I plan on 100 watts, and I'd like to use small wire to
make the wire less visable, but using the maximum
SPAN of 1000 feet with #12 wire, the chart says that
to keep the sag less than 50 feet, I need 400 pounds
of tension (as if I could every supply that force!),
but the recommended #12 tension is only 75 pounds.
using something as large as #12 wire,
for the maximum table SPAN of 1000 feet,
(my actual SPAN is 400 meters)
the chart says that to keep the sag to less
than 50 feet, I'd have 400 pounds of tension;
unfortunately, the recommmended tension is
only 75 pounds (at 10% of breaking strength).
Or, my tension would be 400/750= 53% of breaking
strength of #12 wire.
So, what can I do? Is there a strong, light wire that
will work for 800 meters with 50 foot sag?
73
Barry, W5GN
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