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[TowerTalk] Orion rotator application note

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Subject: [TowerTalk] Orion rotator application note
From: (dan hearn)
Date: Mon, 22 Mar 1999 18:18:19 -0800
During a conversation w Mike a week ago he said that M2 abandoned the rubber
donut shock absorber because the bolts loosened and gave trouble. He also said
that rotator mounting bolt loosening is a frequent problem. They have supplied
some commercial rotator systems w drilled head aircraft grade bolts safety 
These are very expensive. He also said they are looking at some sort of sheet
metal plate with bend up tabs as used on some automobile assemblies. He 
using RTV on the bolt heads rather than Loctite. This can be cut away with a
knife if removal is necessary. He feels that it is necessary to periodically do
maintenance tightening of bolts.
  I wonder if the different thermal coefficients of aluminum and steel cause 
of these problems. I like the use of lock washers to accomodate small 
changes w temperature. Double nutting, as suggested by Steve , is certainly a
good practice.  73, Dan, N5AR wrote:

> Greetings, TowerTalkians --
>       Other than a prop pitch, the Orion 2800 is about the best amateur
> rotator available but I've run across three Orions in the last couple of
> months with the same problem. And that is, in spite of having the best and
> beefiest mast clamp in the world, all three of them had loosened up and the
> antennas were being turned by the wind. One was a TH11, one was a C-4XL and
> the other was an M2 2L 75M yagi.
>        In all cases, the nuts on the long bolts through the mast clamp had
> loosened up. And all of these nuts were the nylock ones supplied by the
> factory and also had spring lockwashers. These were both versions - the fine
> threaded and the coarse threaded ones so they are both subject to the same
> problem.
>      While re-tightening them is great, I think it is inevitable that they'll
> loosen up again. In the case of the 2L 75M, it went through almost 2 winters
> before coming loose.
>      Anyone using this rotator should plan on taking added precautions to
> prevent this. In my cases, I'm going to double-nut everything. Another option
> would be to use some Locktite (sorry - I can't remember if it's the blue or
> red to use). Or do both. In any case, you won't be sorry.
> Cheers,  Steve   K7LXC
> --
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