Cornell Dubilier CDR Rotor Model AR-22

  1. Controller Label showing Model, Series and Serial Number
  2. Service Manual
  3. Schematics
  4. Wire Layout
  5. Parts
  6. The Initial Pulldown
  7. Initial Inspection
  8. Transformer Power Considerations
  9. Transformer
  10. Lamps
  11. Controlacitorler Capacitor
  12. Some Motor Theory- The Permanant Split Capacitor Motor


This is a description of the first stage of restoring a Cornell Dubilier Model AR-22 Rotor and Controller. More to come when I have gathered some parts.

Thanks to the generous advise from members of the Bribane Amateur Radio Club. In particular, Ash VK4ASH, Bob VK4BXI, Graham VK4CEG, and Lin VK4VVK who gave me the project.


Controller Label showing Model, Series and Serial Number



Service Manual


Cornell Dubilier Service Manual: cornell-dubilier_electronics_ar-22_antenna_rotator.pdf






Wire Layout






The Initial Pulldown




Initial Inspection

After pulling the cover off and cleaning off some dirt these are some initial observations.


Transformer Power Considerations

You can probably power the motors from a 24V ac transformer. Motors might be a bit slower, but use good think wire to reduce the losses up the tower. You can probably use use a simple DC/DC converter powered from a rectified 24v supply to do the direction sensing. The motors will need AC for drive though.

If you add up the (DC) resistance in the drive side (4R + 0R75 + 2R5) gives 7R25. Means that (very very roughly) the max current that can flow is 3.6A (at DC) but trying to get an idea of sizing of transformer.. so 86VA, so see if you can find a 100VA transformer? This is likely a very high over estimate given the size of the transformer

12v plus 12v transformers are common. 2 * 12V * 3Amps or 80VA would probably work well.

As it is an AC motor the volts won't matter too much (unless you have long lead length to tower) The speed will aways be the is driven by 50 hz. The motor cap is important to get right. In theory what you want is the same current in both phases of the motor but phase displaced at 90 degrees. This is gets messed up by the resistance of cabling to the rotator with different lengths and different conductor sizing. In practise it will work some how, but the phase shift and how well the two phase currents are balenced will determine how much torque the motor will produce. So any volts from ~15 volts upward will work. If you are testing with very short cable length currents will be high the motor will be noisy and overheat quickly.

Note that both the transformer and the motor are short time rated, so I seem to remember ~3 amps phase current X2 and ~20 volts so 60 VA continous but anything over 40 VA would be fine (then the motor will burn out first !!)

It is probably okay to just match the "size" as I am pretty sure the power rating is mostly the iron cross-section and the windings are then adapted to the outputs requried.




The transformer indentification 10066503 ACU-150 do not reveal any information on Google, so I assume that it will be a custom transformer.


  1. Ground - Black
  2. Active - Brown
  3. Neutral - Blue
  4. 6 VAC - Black
  5. 34 34VAC - Yellow
There is also likley a thermoswitch included in the windings.

Looks like one tap only supplies the two 6v lamps. Lamps light on 6v on a test PSU. By the schematic and test onstructions below the other tap is 354VAC and goes to the rotor only. All the controller switching must be supplied on the return connecting wires.

To test the voltage levels, disconnect the control cable and with the A.C. line cord plugged in, and the control knob turned to the right or Left of the red pointer, a voltage check should show 34 volts A.C., between terminals one and the metal chassis and 6.5 volts A.C. between termina two and the chassis.



There are two Lamps, one either side of the front bezel to illuminate the dial.



Controlacitorler Capacitor

This a double capacitor in a single enclosure. It is likely essencial for phase shift to drive the rotor motor.

Cap-3-three-pins.jpg Cap-3-three-pins.jpg Cap-3-three-pins.jpg Cap-3-three-pins.jpg

This capacitor may require replacing due to it age.


Some Motor Theory- The Permanant Split Capacitor Motor

Types of Electric Motors:
Types-of-AC-Motors.png Source:

When the power supply is turned on, the current flows first in the main winding and then, with a short delay due to the capacitor, in the secondary winding. This difference in the main and secondary winding currents takes the form of a phase difference (meaning their waveforms are offset from one another on the time axis), causing the peak magnetic field to alternate between the two windings and thereby generating a torque that starts the motor rotation.

This type of motor is somple but suffer from low efficiency due to energy losses from heat generated in capacitor. Capacitor may need periodic replacemnt. They also tend to be noisy and chatter as it is difficult to maintain the optium phase shift.

PSC-motor-01.jpg PSC-motor-02.jpg

Glenn Lyons VK4PK
Ver:gnl20220926 - pre published v0.9