[TowerTalk] 204BA loose clamps
Tue, 20 May 1997 02:48:54 -0400 (EDT)
I came home from Dayton to find the reflector of my 204BA sagging from the
first element joint (a few feet out from the boom). I recognized the problem
immediately -- a few months ago the same thing happened to one of the other
elements, though that one slid all the way out before I could get up to fix
it. The element in both cases had slid out far enough out of the element in
which it was seated to start bending downward (or falling out completely in
the latter case).
I went up the tower Monday and discovered another problem as I was about to
fix the reflector. The nut and lockwasher had fallen off the bolt that goes
through the boom midway between the directors, and the bolt had worked
itself loose from one side of the boom, sticking out about an inch and a
half on the other side. The bolt holds two parts of the boom together where
one swaged piece fits into the center portion of the boom. (A top stay would
have prevented the boom from separating completely had the bolt dropped out
3.5 hours later the element and boom were repaired (it was a windy day).
The antenna was purchased used around 1978. In 1981, I replaced the original
(rusty) hardware with a kit of stainless steel available at the time. The
element clamps are C types, with the end of the C clamped tight on the
element by a bolt, lockwasher and square nut. Ribs on the nut side of the
clamp prevent the square nut from turning once it has been tightened down.
The antenna was up for 10 years at 100 feet at my old QTH in Bear, Del., and
has been up at this QTH for the past six years, most of the time at 120
feet. My questions:
1) Is the element problem (vibrating loose) common with this type of clamp?
In neither case where the element worked loose was the clamp noticably
loose; in fact today I had to loosen the clamp considerably before I could
re-seat the outer element into the larger, inner element piece.
2) Is there some kind of metal fatigue occurring because of the age of the
3) Should I replace all the C clamps with all-stainless hose clamps? Would
they be less likely to work loose?
4) Should I insert ropes in the elements to dampen vibrations? (there are
I checked all the other joints that I could reach from the tower today and
the outer ones were checked visually. None of these seemed loose. But I plan
to bring the antenna down to ground this summer and re-check everything.
Your thoughts on how to improve the antennas durability will be appreciated.
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Administrative requests: towertalk-REQUEST@contesting.com