About 27 years ago, I helped build a contest station where we used mostly
stacked HyGain monoband antennas, and a pair of Cushcraft shorty fortys.
On the Shorty Fortys, the hose clamps were tightened at the point before the
clamp stripped (subjective trial and error). Unfortunately over the years,
three of the element tips have fallen out of the loading coil section. None
of the clamps appeared to have failed. This could be due to any number of
things, but the point is, out of 8 elements, 3 have failed.
About a year or so later, I put a Cushcraft shorty forty up at my place.
However, I bought aluminum sheet metal screws and placed one at each
section. To date, I have had no degradation of the antenna or elements
dropping out. Other than a lightning strike blowing one of the loading
coils to smithereens, its still working fine.
Just a side note.
The HiGain antennas used the clamps that used stainless steel single bolt
into a nut that when tightened compressed the outer element. They still may
be using this, I don't know. Even though the screw was oiled, little did we
know that a few of those bolts actually seized before being tightened enough
to adequately hold the end of the element in place over time. Whoever
assembled the elements didn't recognize the problem. Apparently the smaller
element did not turn inside the larger element when tested. If using these
clamps, make darn sure this doesn't happen to you.
Jim - KR9U
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