[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

re: counterweights

Hi all,
I have been experimenting with the mechanical
aspects of my future satellite antenna installation....

40 ele 70 cm--------6 foot dish----------------22 ele 2 m

on a 12 foot 1 1/2 fiberglass boom. * I tried using an
off center mount on the yagi antennas to act as a partial 
counterweight for the dish, but this introduces a significant
amount of twist in the boom.*  I think this twist will make
final alignment of the array really difficult. 
I think, at least with this heavy set-up, that each yagi should be
mounted at its own balance point, and a counterweight used
to balance the dish. The only problem now is that the
counterweight places the weight of the assembly way
over the rotor's rating for vertical load. 

                                 6 foot dish
40 ele 70 cm---------elev rotor----------------22 ele 2 m
                       "              *              "
                       "              *              " 
                       "              *              "
                       "              *              "
                       " ============="

So I am adding this steel crossarm with vertical support arms to
take most of the weight off the rotor. Each support can be
shortened or lengthened for final adjustment, and the 
counterweights for the dish will nest right in-between the 
mast and the supports. I am going to try using an 1 1/2
pvc tee for the support to crossboom bearings, and make the
supports themselves out of 1" allthread or something. 


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.

Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org