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W1KRK
03-20-2011, 01:37 PM
Recently installed a new Ham IV, Calibration instruction are vague, I can't get my beam to point in the same direction as indicated on the control box. There is also a switch on the rear panel but no mention in the manual. Do I have to rotate the mast to 180 deg ccw, and move the antenna to point that way. Need help.
Thanks.

K9STH
03-20-2011, 03:55 PM
You have to move the antenna so that it points in the direction that is shown on the indicator. Most people set the indicator to show north and then physically move the antenna (by loosening the "U" bolts on the rotor and turning the array to point north and then re-tightening the "U" bolts). There is no way that you can adjust the indicator from the ground.

The Ham-IV rotor rotates approximately 360 degrees. At either end of the rotation there is a switch activated by a "cam" inside the rotor which disconnects the voltage and then you can only rotate it in the opposite direction for a few degrees when the switch again connects and you can rotate it in the "other" direction again.

Glen, K9STH

KT0DX
03-20-2011, 03:57 PM
Operate the rotor box until it is on North. Shut off the rotor box and go outside and loosen the antenna from the mast and turn it until the antenna is pointing North and tighten everything back up. Your indicator on the rotor box and the antenna will now be set up correctly. The calibration is for fine adjustments such as when you check the antenna with a compass and it is off say 5 degrees you can make the necessary correction from the rotor.

Steve
KT0DX

WB2WIK
03-20-2011, 04:52 PM
Operate the rotor box until it is on North. Shut off the rotor box and go outside and loosen the antenna from the mast and turn it until the antenna is pointing North and tighten everything back up. Your indicator on the rotor box and the antenna will now be set up correctly. The calibration is for fine adjustments such as when you check the antenna with a compass and it is off say 5 degrees you can make the necessary correction from the rotor.

Steve
KT0DX

Actually, that's not even what it's for. The "calibration" is purely mechanical, when you set up the antenna and clamp the mast into the rotator in the correct position. The CALIBRATE control is to set the meter to full-scale (exactly to the 180 degree mark) after pushing in the calibrator set switch, to make up for variations in AC line voltage to the control box. The power supply used to drive the meter is not well regulated (it's just somewhat regulated by a single zener diode) and the "zero set" can drift with time, temperature and line voltage. That's really all the CAL pot is for.

WA7PRC
03-20-2011, 05:49 PM
The instructions are quite clear. From the Ham IV user manual (http://www.hy-gain.com/man/pdf/HAM-IV.pdf), page 6:


Return the rotator to the full CW "S" position. Mount the beam to the mast pointing South.
and page 9,

2. Depress the brake lever (center) and hold. Depress the CCW lever (left) and operate the rotator to its full CCW position.

3. With the rotator in its full CCW position, if the meter is not at its full left position, carefully adjust the zero (CCW South) position with the screw directly under the meter to exactly South.

4. Meter Calibration Procedure: Operate the rotator to the full clockwise position. Adjust the calibration potentiometer until the meter indicates full scale to the right. The meter is now calibrated. Do not adjust the calibration potentiometer when the rotator is in any posiion other than full clockwise.

K0BX
03-24-2011, 06:24 PM
I just wonder if your control box may have a Rotor-EZ control board in it?

The switch on the back could be for a second beam heading. On some mast, Hams will have one antenna pointed North, and a second antenna pointed East. The rotor-ez board will allow the meter to show correctly the position of each beam depending on the position of the switch.

I would open up the control box and look for the circuit board. If it is a small board with only a fuse holder and some other parts, then it is the original board, if there is a board mounted on the back of the meter with some IC's on it, then it is the Rotor-EZ board.

Joe K0BX

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