,

Today I got a Alliance tenna-rotor (that's what on the back).

From descriptions I got from the internet I can conclude that
it will probably be a Alliance U-100 type rotor.
(the rotating mast can go completely through the rotor,
I want to use it for elevation control)

Carefully I opened the box to see what's inside.

You have four conductors comming out of the control wire,
only three are connected:

black red
input cable O O TOP VIEW
----------------- none blue
O O

I think it needs 24V DC.
Which one should be the mass, and which are the 2 for left-right control?

What I'm planning to do:
- Make a computer interface to controll the rotor for elevation.

Do I need to insert a variable resistor to see what's the rotor position?
If yes, how do I do this ?

Another thing is the interface, which designs should I use ?


Most of the rotators use an AC voltage and a a capacitor.
The winding is center tapped. one side of the low voltage AC goes to the
center tap. The capacitor is across the whole winding. To go left or
right, the other AC lead goes to one of the capacitor/winding leads and the
other end is left floating with just the capacitor attached.

For a vertical mount you can attach a variatable resistor to the rotating
part and hang a weight on the shaft of the resistor.

Look in the www.amsat.org programs and look for a program called fodtrack.
In it is a simple computer interface that works off the parallel port of a
computer. YOu should be able to get some ideas from there.