For dipoles, and particularly the Carolina Windoms, I always make
sure I have a center support, normally a tree. However, in one
case I have the center support via a pulley placed out on a limb
about 65' up.
The obvious advantage is supporting the weight and eliminating
sag. The other thing it does (not at all related to ham radio)
is to make everything look a lot neater in a suburban yard.
Having the feedline come down close to a tree is a lot less
noticeable than one hanging out in the open.
The biggest mechanical problem with the Carolina Windom is the
weight of the coax and baluns working to pull the coax out of the
various coax connectors. I have remedied this by using
Kevlar/Dacron string tied around the base of the baluns and then
around the coax about a foot below the baluns. I just tie it and
tape it to the coax and adjust the tension so that there is just
a slight upward pull on the coax, taking the stress off of the
connector. So far this method has worked perfectly for about
2-years. No coax connector failures although there has been
plenty of wind and lots of tree movement.
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Eugene
Hertz
Sent: Wednesday, October 11, 2006 9:16 AM
To: TowerTalk@contesting.com
Subject: [TowerTalk] Stringing dipoles?
Ok, this may be the simplest question I will ever ask here so
here goes.
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. Several folks I've
corresponded with indicated that they attempted to "lift up" the
feedpoint as high as possible by putting more tension on the
wires (legs) to hoist it higher. This was for people that did
not have a convenient center mounting location like a tower or
tree or house.
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.
My thought was this: By using one rope (dacron etc) to connect
leg1 to a tree and another rope to connect to leg2 to a tree
(with pulleys and weights, of course), this is putting lots of
"horizontal" stress on these wires and the center matching
conductor/insulator thingy. This force is always trying to pull
apart the antenna.
Why not take one very long rope, thread it through the leg1
insulator, the center insulator/matching unit and then the leg2
insulator? Surely the two ends of the wires would have to be
attached somewhat taught to the rope, but this could be done with
some black wire-ties along the length of each wire. Or tie some
knots in the rope somehow to hold the insulators in place.
My thought was, this would all but eliminate any horizonatal
stress normally put onto these wires and we would be left only
with the stress of gravity vertically. I would imagine too, that
this would help keep the center up a big better than nothing
going through the center point.
Any thoughts? Could this work? What am I missing?
Eugene
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