[TowerTalk] Mast slippage

[WA9ALS - John]

Hard to imagine, but if there's anyone out there less experienced than me in
this TT game, be careful what you use in your rotator's jaws, and follow the
LXC directive.  The post below sounds like a great idea, and my
understanding is that it would work for the Yaesu rotors.  However, it would
NOT work for a T2X, for example.  Depending on mast diameter, any
significant thickness of "pads" will put the center of rotation off center.
For my mast, 0.071 inch of shim on the rotator body side (fixed side) is
required, so I can't just put anything in there.  I plan to use stainless of
known diameter, and I'll probably pin the mast, per manufacturer's recs.
(I'll let you know when it breaks!)  73

WA9ALS - John
jfleming@shelbynet.net
Tower Project Guestbook http://www.shelbynet.net/~jfleming/towerproject.htm
Amateur Homepage http://www.shelbynet.net/~jfleming/amstart.htm

----- Original Message -----
From: dan hearn <dhearn@ix.netcom.com>
To: <towertalk@contesting.com>
Sent: Wednesday, September 15, 1999 11:45 AM
Subject: [TowerTalk] Mast slippage


>
> 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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>


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