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Dish orientation and wind loading



Hi folks,

Ok, so Winter's coming, and believe it or not, there *are* seasons
in California.  While I'm not worried about snow collecting in my
canned helix, I am worried about the wind.

The normal park position for my rotor is due South.  That's where
the club's repeater is, and perhaps more importantly, that's where
most storms come from around here.  When all I had were a couple of
beams, this presented the minimal wind load.  Now I have this 30x36"
screen covered grill up there to add to the wind problem.

I believe that having the grill point straight up would present the
minimum wind loading for it, but that would put the two beams at
probably the worst orientation - high and broadside to any wind.

I know that the window screen I used on the grill isn't as bad as
putting a solid dish up there, but it's still going to be pretty bad.
I read something years ago that mesh C-band dish was as good as solid
as far as the wind was concerned.

So, two questions:

1) how much force will a 30x36" screened grill put on the tower in,
say, a 50 mph wind?

2) given that I have to pick a compromise direction to park the rotor,
what is best?  The other antennas are a 8 element 2 meter beam
(vertically polarized), and a 2x8 element 70cm beam.  You can see
what I've got at:  http://www.jps.net/gregd/hamsite.htm

I'm going to guess that the beams are going to contribute less than
the dish, so parking the rotor either due east or west (putting the
dish in profile, but the beams broadside) will be best.

Comments?

Thanks,

Greg  KO6TH


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