[amsat-bb] Re: Non linear rotator

i8cvs domenico.i8cvs at tin.it
Mon Mar 15 06:22:14 PDT 2010

----- Original Message -----
From: "Phil" <phillor at telstra.com>
To: <amsat-bb at amsat.org>
Sent: Monday, March 15, 2010 3:28 AM
Subject: [amsat-bb] Non linear rotator

> Thank you for reading this.
> I'm trying to devise an equation to correct the rotation of my non linear
> rotator. It's correct in the middle of its range but out at both ends of
> travel. I asked this same question ten years ago and someone kindly told
> about a simple Window application that did exactly want I wanted.
> I have searched through my e-mails back to 2000 and cannot find the reply.
> Can anyone, once again, suggest a suitable Windows or a Linux application?
> --
> Regards,
> Phil
Hi Phil,

I guess that your rotator is an azimuth rotator of the class G-400RC
or G-450XL using only two wires from the rotator potentiometer to the
control box terminals 2 and 3

In this type of rotator the non linear position using automatic traking
arise from the fact that the current flowing into the rotator potentiometer
is not a constant current but it depends on the antenna position.

If this is the case I have designed the hardware solution of the above
linearity problem adding a constant current regulator into the control
box that allow the current flowing into the rotator potentiometer to stay
constant for any antenna position.

If you are interested on it I can send to you the schematic diagram.

Best 73" de

i8CVS Domenico

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