[NLRS] Elevation rotators for small stuff

[Dr. Gerald N. Johnson]

Even 0.5 RPM is a bit fast for a dish at 10 GHz. If it can be slowed it 
might be useful. Servo motors usually can be slowed. N5AC wrote in a 
CSVHF proceedings a few years ago about using servo motors to slow and 
hold a 1 meter 10G dish for roving.

Look at www.surpluscenter.com for light duty linear actuators at fairly 
reasonable prices. Many a C band dish has been moved with such linear 
actuators, essentially a motor geared to a screw thread with a traveling 
nut.

It has been suggested to use the print head moving stepper motor from a 
dot matrix printer. With simple controls (digital) motor steps can be 
fairly small linked to a dish moving lever arm by the original printer 
cogged belt. Its very practical to divide a stepping motor's steps by 
applying currents to the two windings approximating two sine waves in 
quadrature with magnitudes set to the sine and cosine of the step angle 
division desired. Called microstepping. The head mover stepper from an 
old floppy drive would probably work too. I recall Axman has moderate 
sized stepping motors by the bushel.

Barry used an electric scissors car jack for elevation on one of his 
tower mounted dishes.

There are many possible and workable solutions, more when the required 
motion is small.

73, Jerry, K0CQ

On 9/4/2013 12:51 PM, w0zq at aol.com wrote:
>
>
>
> I have been thinking of a low cost solution for remote elevation for small dishes, maybe like horns to 14" dishes, maybe for roving.   The standard elevation rotators out there are overkill and expensive.  A U100 or U110 may fit the bill, but "new" they are around $100.   I was wondering if anyone has any experience with using a small low rpm motor like those available at ServoCity and other sites.   For example, they offer a 12 vdc 0.5 rpm motor for $25.   Max torque is spec'ed at 3,000 oz-in.  http://www.servocity.com/html/0_5_rpm_gear_motor.html  .   Anyone have any experience with such a small low rpm motor .... good enough to control the elevation on a small uW dish ?   Yes, some assembly would be required.
>
> 73, Jon
> W0ZQ
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