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[TowerTalk] Long Masts -- Intermediate Bearing?

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Subject: [TowerTalk] Long Masts -- Intermediate Bearing?
From: (K7BG Matt Trott)
Date: Fri, 3 Apr 1998 23:31:33 -0700 (MST)
>     With a long mast and an aggressive antenna load on it so that the mast is
>VERY top-heavy, the problem becomes how to hold the bottom of the mast in case
>you have to swap out the rotator or similar situation. You can have some sort
>of fixture to hold it but most people use an additional accessory shelf with
>an additional thrust bearing. That way the mast is always captured. This'll
>work on 45G and 55G but not 25G. 

Steve, Are you saying an add'l shelf with thrust bearing won't work on 25G?
I was just wondering in case I ever decide to put up some 25G.
FWIW, when I put up my 83' of 45G, I used an add'l accessory shelf above the
rotor with a hard wood bushing (piece of oak with circle sawed in it) to
provide lateral support for the 20' 4130 CM mast. I was too cheap to buy
another bearing. There is 8 feet of mast inside the tower.

I trammed by hooking the line directly to the mast. I had muffler clamps
secured both above and below the hard wood block while raising the first
antenna before before installing the rotor. Didn't back guy (CM 4130 mast).
Pulled up a 402CD and a 205BAS. Worked great even with no ground crew. Just
pulled the antennas up, tied off the rope and climbed the tower and bolted
'em on. This was after careful planning and thinking and rethinking all
steps. This is not an area to throw care to the wind!

73, Matt--K7BG

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