In a message dated 5/20/01 11:05:44 AM Pacific Daylight Time,
jerryc@netscope.net writes:
> I am almost ready to put up my little 40' guyed tower. Everything is here
> or on the
> ups truck. There is a lot of discussion on mast stress and material type
> but haven't
> seen anything on how far the rotor should be below the thrust bearing. I
> am using 2" o.d.
> x 3/16" wall sae 1026 tuning. It came from the steel supplier at 21'-6"
> long. I am mounting
> a 4 el 10M vee (elements are up on 45 degrees on each side of boom)
circular
> polarized antenna
> 10' above the tower top. The rotor is a Yaesu G800SA. In the future I
will
> probable remove
> the 4el 10M vee and install a 3 el tri-bander about three feet up and put a
> small vhf stack on top.
>
> How far down should the rotor be located in relation to the height of mast
> above the thrust bearing?
> I could use the whole mast but would rather minimize the weight. I want
the
> rotor far enough down
> to minimize the side load on it.
I'm not sure what length of mast you're intending to use. If you're going
to use the whole length, I'd go for approximately 1/3 in the tower and 2/3
sticking out the top. If you're just going to use enough to get your antenna
10-feet above the tower, I'd still go with the above ratio.
There isn't enough rotator sideload to worry about either way.
Cheers, Steve K7LXC
Tower Tech
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