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Re: Cross Boom (new twist)



Hello the net:

I assemble the complete fiberglas  horizontal boom on saw horses on the 
ground with all of the antennas and antenna feed lines mounted.

I first add the the antennas that will be either rear mounted like a 
rear mount yagi or dish antennas like the gridded 2.4 GHz antenna.

Then I add the 2M  and 70cm yagi antennas, at either end, adjusting the 
position of the mast to boom clamp for front to rear balance.
Same with the 1.2 GHz yagis.

for side to side balance (because the 2M cross pol is heavier than the 
70cm cross pol,) I adjust the rear mount antennas
 or the 1.2 Ghz antenna for side to side balance.

After I achieve reasonable front to rear and side to side balance,
I mark the aluminum dowel on the top with an adjacent mark on the 
fiberglas tubes.
I split the fiberglas masts from the aluminum dowel, and  set the 
elevation rotator to zero degrees elevation.
Install the dowel on the elevation rotator on the tower, marks are up, 
then install one fiberglas pole at a time.

Since the elevation rotator has slop in its gear train a slight 
imbalance forward or rearward,
 would prevent a wobble, if a perfect balance were present.

I do not use any other weight, other than the antennas.

If I were going to use a  big dish only, I would consider a torque arm 
to the rear of the elevation rotator to counterbalance.

For much bigger elevation rotators, the elevation motor current to 
elevate should be about the same as to depress.

Stan, WA1ECF    FN41sr  CApe Cod




John Becker wrote:

>When Is a counterweight needed to be added ?
>
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>


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