[amsat-bb] Re: inquiry about homebrew az-el systems

Michael Mat_62 at charter.net
Thu Feb 28 15:02:01 PST 2013

This is what I was getting at when I made my earlier post about about 
the old Gemini OR-360 TV rotators.  The gear train is driven by a "540" 
sized  DC motor. I can tell you from experience that one of these rotors 
will rotate a mini sized beam on HF.  I do it everyday. So if we are 
driving a smaller array, we might be able to eliminate some or all of 
the gearing involved and go with one of the smaller motors. I can't 
recall the issue but it seems to me I saw an article in QST where 
someone was driving a small little beam on top of a tripod with a small 
little motor.  I still think a position pot is a better option for 
pointing over a stepper motor though.
Michael, W4HIJ
On 2/27/2013 8:30 PM, Gus wrote:
> Returning to this topic...
> I'm thinking about a rotator that can handle a small system like the 
> Arrow, or the Cushcraft A270-6s or even the A270-10s.  NOT big boomers 
> like the KLM 22/40 el CP yagis!
> So we're looking at 1½ - 2 sq. ft of windloading, and maybe 10 lbs of 
> weight.  (Including some sort of crossboom, clamps, coax and 
> counterweights.  Rear mounted antennas like the Arrow will need a 
> rear-mounted counterweight.)
> Anybody qualified to say what that adds up to in terms of TORQUE 
> required from the motors?  With a little extra thrown in for a safety 
> margin, maybe?
> I think a simple, low-cost, easily reproducible design is probably 
> doable, if we combine our ingenuity and expertise.
> -- 73, de Gus 8P6SM
> Barbados, the easternmost isle.
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