CDE/HAM IV Rotor Control

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by VE2CY, Aug 31, 2019.

ad: L-HROutlet
ad: l-rl
ad: Left-3
ad: abrind-2
ad: L-MFJ
ad: Left-2
ad: Subscribe
  1. VE2CY

    VE2CY Ham Member QRZ Page

    I have a CDE rotor control box, the predecessor of the Ham IV. One day, the meter needle started randomly jumping all over the place, whether turning the antenna or not ! It just moves randomly (when it moves) but the antenna accurately follows my rotate left or rotate right actions.

    I believe this would indicate a problem in the box, but the circuitry is very simple, and the antenna turns as it should. I just have to go outside to verify the direction, lol.

    Has someone seen this problem before? Is the wacky reading coming from the control box, or the potentiometer in the rotor itself ?

  2. K9STH

    K9STH Ham Member QRZ Page

    Make sure that the 8 terminals, where the rotor wires connect, are good and tight. In fact, loosen each terminal and then re-tighten the machine screw.

    You might be able to check the 500-ohm potentiometer in the rotor itself by disconnecting the wires from Pins 1, 3, and 7. Put an ohmmeter across the wires from Pin-1 and Pin-3 and see if the reading "jumps around". Then, from Pin-1 to Pin-7 and finally from Pin-3 to Pin-7. The first 2-readings can be anywhere from almost 0 ohms to slightly over 500 ohms and the sum of the readings should be around 500-ohms. The 3rd reading should be around 500-ohms. If any of these readings is not steady, then there are 3 possibilities: The first is a broken wire in the cable which is making and breaking. The 2nd is an intermittent connection between the control cable and the rotor. The 3rd is something wrong in the rotor itself including an intermittent potentiometer, dirt on the potentiometer, corroded connection, etc.

    There are also a couple of potentiometers inside the control box that may have become dirty and that will not show up when checking the wires. After cleaning, re-calibrate the control box per the instructions in the manual.

    There were 3-versions of the Ham- rotors before the Ham IV. Those were the original Ham-M, the Ham II, and the Ham III. All are basically the same with different control box layouts. The manuals for each of them can be found on BAMA at the following URLs:


    Ham II:

    Ham III:

    Glen, K9STH
  3. AA4PB

    AA4PB Ham Member QRZ Page

    It is a common problem that the pot inside the rotor becomes worn and intermittent, causing the direction meter to jump around. It has been my experience that the wires on the pot actually wear down to the point where they no longer make good contact with the arm rather than just becoming dirty thus the pot has to be replaced. That's not to say that you couldn't have intermittent connections elsewhere so it would be a good idea to check those first since they are easier to get to.
  4. VE2CY

    VE2CY Ham Member QRZ Page

    Thank you K9STH and AA4PB - that gives me a few things to check from both of you.
    Given that it is a very old rotor, it could well be the pot in the rotor itself. It is a bit odd that it worked perfectly, then started "going bananas", at least as far as the meter goes - as I say it rotates reliably and calmly, hi hi.
    The jumping around occurs whether I am moving it, or it is stopped - would this be more mechanical or electrical I wonder. This is no physical movement anywhere to "jostle" the wires.
    Anyway, I will try measuring 1,3 and 7, and see what I get !
  5. K9STH

    K9STH Ham Member QRZ Page

    If you have never taken any of the Ham- rotors apart, be VERY careful!

    Put the rotor inside a cardboard box before pulling it apart. There are 96 ball bearings inside and they WILL go all over the place when the rotor is disassembled. The purpose of the box is to catch all of the bearings.

    Usually, the bearing are in good shape and can be reused. However, while you have the rotor apart, replace the "pot metal" ring gear with one of the new steel bearings that are available and are now used in the Ham IV versions. They are completely compatible with the old type and will definitely hold up a LOT longer than the original "pot metal" ring gears.

    Glen, K9STH
  6. VE2CY

    VE2CY Ham Member QRZ Page

    Hello Glen - you gave me a giggle as I pictured 96 ball bearings bouncing around the basement floor! (you are right, I have never taken one apart) … thanks for the warning!

  7. K9STH

    K9STH Ham Member QRZ Page

    The ball bearings are held in place by 2-each plastic holders. However, when the rotor is disassembled, a number of the bearings seem to go every which way. If not contained, there will always be at least one, usually more, that you never find.

    Before reinstalling, clean the bearings and the holders. Then, use a quality grease when putting the bearings back into the holders. Be very gentle when reinstalling so that the bearings stay in the holder.

    Although I no longer have any of the Ham- rotors around, when I did, I had to replace the ring gear every-so-often and that required disassembly. I still have 2-each of the lighter AR-22 rotors both of which are going on 60-years old. One of them is on my "short" tower turning my VHF antennas and the other is on the ground right now. Those rotors are the Energizer Bunnies of rotors. They just keep going and going and going!

    One thing about the CDE (now mfj / HyGain) rotors is the starting capacitor in the control box. Those wear out on a regular basis. If you replace the original 50-volt capacitor with a 120-volt capacitor (available at electric supply houses, Grainger, etc.), of around the same value, the capacitor will last a LOT longer. Also, the 120-volt capacitors are actually cheaper from the commercial sources than the 50-volt capacitors sold as replacements for the rotors.

    The 120-volt capacitor is physically larger than the 50-volt capacitor but there is plenty of room in the control box. Also, the 120-volt capacitor has "push on" connectors and new connectors come with the capacitor. Just cut off the original capacitor wires right at the capacitor, strip the ends of the wires, put into the new connectors, and "crimp" with a pair of pliers or solder. Since the starting capacitors are not polarized, it doesn't matter which wire goes to which capacitor terminal.

    Glen, K9STH
  8. WA7ARK

    WA7ARK Ham Member QRZ Page

    I just put up a Ham IV. Here is how I did the capacitorectomy....

    I mounted a modern 120V motor starting capacitor right under the shelf that the rotor sits on (up the tower). That saves two wires in the control cable, which can be paralleled with the existing brake wires to reduce the voltage drop to the motor/brake wires. Seems to have a bit more starting torque because of the new capacitor and the elimination of the IR drop on the capacitor wires. (Yes, I weatherproofed the capacitor).

    I also moded the control box to add an automatic brake delay (holds up the brake until the rotor coasts to a stop).
    Last edited: Sep 1, 2019
  9. VE2CY

    VE2CY Ham Member QRZ Page

    Interesting Mike - but I'm slowly developing "tower fright" at my older age and am a bit leary of that modification, lol ...

    Glen, I just got around to trying your suggestion about wires 1,3 and 7. On my little Micronta, it worked out just as you said - 1,3 resistance and 1,7 resistance added up to 500 ohms, and 1,7 was 500 ohms. Like I said, the "control" part is 100%, it is just the meter which is sporadic. When I rotate left or right, it's like it is not paying attention, then it jumps 10/15 degrees, then floats back and forth like a butterfly (sorry Cassius), and flutters part time, then is steady. (Same when I am not rotating the antenna, and there is no wind today). If I push calibrate, it goes down to South (right side). Can a flaky Rotor Pot do that?
  10. K9STH

    K9STH Ham Member QRZ Page


    Before you eliminate the potentiometer, with the wires disconnected from the control box, connect 1-lead of the ohmmeter to Pin-3 and the other to either Pin-1 or Pin-7. Then rotate the unit and see if the resistance changes smoothly or jumps around. If it jumps around, then you do have problems with the potentiometer.

    Glen, K9STH

Share This Page