----- Original Message ----- From: "Phil" phillor@telstra.com To: amsat-bb@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

its

travel. I asked this same question ten years ago and someone kindly told

me

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