From: "Eugene Hertz" <ehertz@tcaf.org>
Subject: [TowerTalk] Stringing dipoles?
During my research for OCF dipoles, I have read about some horror stories of
dipoles breaking or coming apart due to the stress of wind, weight and other
factors. Especially I've heard that the carolina windoms, with their extra
weight in the center caused by the matching unit, the isolator, and the
length of feedline can cause a big sag at the feedpoint.
In thinking about this, it seems that these antennas have lots of phyiscal
stress on them from both gravity as well as tension on the ends of the wires
in the horizontal plane to try to counteract gavity.
-0-
Eugene,
This is a NON problem. I've had multiple dipoles, G5RV's, double G5RV's, CW
160's and CW80's up for years.
Although there are small differences in weight and sag, I've seen nothing
appreciable. It IS true that
you have to put some force on things, if you don't have a center support.
I've experimented with varying schemes...pulleys, weights, bungie cords,
continuous loop haliards, etc.
At the end of the day, I've found it easiest to keep it as simple as
possible, and just put the damned thing up.
I shoot an arrow over each tree, and pull up 1/8" dacron line. It takes
maybe 20 lbs pull to get things up
there and tight. If there's a big blow coming, I slack off on one haliard
by 2 or 3 feet, to allow for
tree movement.
I have had TWO failures, since 1959. One, in VT, was a double G5RV made
from #14 soft drawn copper.
It simply extruded to the point of brittleness, and failed. The other was
#14 flexweave CW80, here in NJ.
In that case, I didn't slack off on the haliard, and had the antenna pulled
tight, when the remains of
hurricane Hugo blew through.
It took less than half an hour to get the thing back up.
N2EA
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