Stan Griffiths wrote:
>
> I doubt that the problem is vibration. Rather, I suspect some misalignment
> between
> the axis of rotation of the rotator and the axis of rotation of the mast. I
> think
> this is the same thing that causes the bolts holding the two cast halves of
> the
> rotator itself to back out. I have had 4 of these rotators up for more than
> 25
> years and I just do not have this problem.
>
> Stan w7ni@teleport.com
>
Hi Stan,
I think this is a sound observation.
Another cause may be misalignment caused by mast flexing inside the
tower, rather than an initial alignment problem.
I know you and I discussed this quite a while back.
This would be more prevalent in towers (using pillow block mast bearing)
that have the rotator mounted at the bottom of the top section. And
would be increased with several antennas attached up the mast, instead
of just one above the tower top.
The likely solution for this type of case would be to use a larger
rotator.
I also think sloppy rotor plate hole fits to fasteners, and use of
non-shouldered (all threads, no solid shank) fasteners encourages the
problem.
--
73, Kurt, K7NV
YagiStress - The Ultimate Software for Yagi Mechanical Design
Visit http://www.freeyellow.com/members3/yagistress/
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