Here is a repeat of a posting I made some time back.
I have been using neoprene rubber pads between the cast aluminum jaws of
my Yaesu 1000SDX rotator and a 20 ft x 0.25 mast on my TX 472 crankup
tower. This accomodates moderate misalignment between mast axis and the
rotator axis. The friction coefficient prevents slippage and distributes
the force on the ridged face of the rotator clamps. It also gives some
protection from sudden impact shocks. The antenna load was a large 4 el
15, a 3 el 10 and a 2 el 20 plus some 2 meter yagis.
This system was taken apart for my move from the Dallas area
(Mckinney) to Deer Park, Wa. recently after 7 years of service. There is
only minimal deterioration of the rubber pads after that amount of
exposure. The pads were made out of a piece of material purchased at a
local farm supply store in McKinney. It is called "baler belting" and
they stock it in 4 inch and , I believe, 8 inch width.It is 1/4 inch
thick. I gave $ 1.60 for a foot of the 4 inch material. It is rugged
looking stuff, similar to the wall of a tire and is rather stiff. I
planned to wrap a piece around the 2 inch mast and clamp down on it. It
is too stiff to do this easily so I compromised and cut 2 pads large
enough to cover the complete surface of the rotator jaws and installed
them. With the jaws very loose, and the bolts only finger tight, I tried
to turn the mast to align it with North. Couldn't budge it due to
friction of the rubber on the mast surface. I had to loosen the bolts to
full out position to make the adjustment. Boy, this stuff really grabs
the mast surface. During my 7 years of use there was no evidence of
slippage at all and you don't have to tighten the bolts very much to
make it work. I am amazed that more hams have not used this scheme
instead of drilling for thru bolts which is , IMHO a poor alternative
with obvious disadvantages. A few of the DFW guys have tried it and it
works fine for them. One tried using radiator hose and it did not last.
I can understand this because the hose is much softer and thinner than
the baler belting. The store where I found this stuff in Mckinney is
called Gebos Blackland and the clerk said they can do mail orders by
UPS. Sorry I do not know their phone number. I think this stuff could be
found in farm stores and probably any store that sells industrial
belting. Possibly somewhere there is hose of a quality suitable for this
job. I would guess it might be for high pressure hydraulic use on big
machinery. At any rate, I had good results with the belting and
installed the same pads on my TX 472 here is Deer Park. If any one has
tried this and had negative experience, I would like to hear about it.
73, Dan, N5AR
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