[TowerTalk] Boom to Mast Slippage

[David Fouchey]

Old Railroad Air Hoses work well like this too and are of similar
construction...

Dave F.
WA4EMR


At 04:13 PM 9/3/98 -0700, dan hearn wrote:
>
>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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>
>

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