Re: [amsat-bb] Old Primestar Dish

[Bruce Nolte N3LSY <brucenol@xxxxxxx>]

Joel Black wrote:
> I have just acquired an old Primestar dish.  It is 43.25" x 39.875".  I have
> measured the area as 1.481 ft^2.  Would this be considered the area for wind
> loading or is this too simplistic?  I had planned to use this with my
> G-5400B rotor, but I don't know if it can handle that much area with wind
> loading.
> 
> Tnx es 73,
> 
> Joel Black, W4JBB

I assume the Primestar dish is a fiberglass offset fed dish.

I would worry some about the wind, but also about the weight. I have had 
a similar sized, but slightly smaller fiberglass dish (34 x 37") on a G 
5400B rotor up for about 6 months where it often receives wind gusts of 
over 30 mph, and have not had problems yet. I also have 22 element and 
40 element KLM cross yagis on it too.

A couple of pointers:

Keep the dish mounted as close to the center of rotation of the azimuth 
rotor as possible. I mounted my dish right next to the rotor, and the 
dish actually rotates over top of the rotor.

  Another good idea is to mount the dish "upside down" so the center of 
gravity sets more over the vertical centerline of the rotor. Also, try 
to keep the dish's mounting point as close to the center of rotation  of 
the elevation rotor as well.

Another suggestion that I have heard, but have yet to implement is to 
add a counterweight to further reduce the torque loading of the 
elevation rotor.

With care the G5400 B should handle the dish with few problems. If high 
winds are predicted, I would refrain from using the dish, and park it so 
it presents a minimum profile to the wind.

73 for now,

Bruce N3LSY

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