Display Degrees of rotation.

[Bobw55]

It is 2 phase AC. I thought about replacing it with a DC motor. It would be easier to have the display unit control the motor as well. This is a small TV antenna style rotator. Because the control unit uses TIME to allow for movement, the pointing accuracy can really vary, and you are mechanically locked into a max of 360 degrees of rotation. Once I figure out a digital display, I am going to remove the mechanical stop. I would like to under rotate by 90 degrees and rotate past 360 by 90 degrees (540 degrees total).

Bob

[aratti]

How much power do you pump into the antenna ?

Al.

[Bobw55]

I only run 50 watts through LMR400 cable. I thought about RF interference, But that can be solved with shielded cable and some roids. Going to grab the rotor off the tower today so I can see where I can mount some sort of sensor.

Bob

[Bobw55]

Well managed to get a pulse disc attached to the end of the motor shaft today. Will have pulses a plenty. Starter question would be:

1) What would I need minimum to just count the pulses and display them assuming I am using a sensor from a mouse?
2) I can mount up to a 2 1/2" disc with a fare amount of divisions on it Was thinking 20 to start.

Sorry to ask so many questions.

Bob

[Dave]

Bobw55 , I have to ask, What kind of rotor are you trying to retrofit? There should be some kind of encoding device already inside. The old alliance rotors had a switch that produced about 50 or so pulses. Cant you just use that one for starters?

Dave Purola,
N8NTA

[Bobw55]

I am using a Phillips rotor and control. There is no feedback in the motor unit. When the controller energizes the motor, it is relying on a constant motion of the motor (1 rpm). The controller has a 2 digit led display to show the position by 10 degree increments, but this is time based only. In the cold and wind and the added weight of the antenna, the position gets off by 20 degrees on a regular basis. It does have the means to re-initialize the rotor and controller by driving the motor CCW for one minute, which in theory drives the motor against a mechanical stop.

I just love a good head scratch-er!

Bob

[Dave]

Bobw55, Wow Bob, I have never seen one like that... It makes sense though. At 60 hertz with the right gearing... I don't know of any way to get the position back from something like that without being concerned about the weather proofing aspect. I might consider some kind of string pot with the string wrapped around the rotating mast. That way you wont have to calibrate it but only once, plus it will give you a linear output. It's always hard to retrofit something that is already built... If you have it down, I would disassemble it and see if there isn't some way to get a pot connected internal... Personally I perfer a pot as a feed back source because of the absolute aspect. Just my thoughts....

Dave Purola,
N8NTA