This is a new one on me. I used to have a CD45-II and I recall it used the
same direction potentiometer in the rotator head that the Ham-M and T2X's
do, which is a wire-wound pot that is very close to linear. I now own two
Ham-M's and a T2X and all indicate direction correctly.
I suggest you try the calibration again.
1) Turn the antenna CCW against the stop and observe the direction of the
antenna. Should be South. Adjust the meter to the left hand S marker using
the zero-center screw on the face of the meter.
2) Turn the antenna CW against the stop and again observe the direction of
the antenna. Ideally it will be South again but may be off a little.
Adjust the calibrate potentiometer so the meter indicates the true direction
of the antenna. That is, if the antenna is pointing 190 degrees (instead of
180 degrees) adjust the meter for a 190 degree indication (this may require
some fudging).
At this point the antenna should track very close to the indicated meter
direction. If not then I would take voltage readings between pins 3, 7 and
1 on the control box terminal strip.
1) Observe pins 3 and 7 voltage. Make this equal to X.
2) Turn rotator until antenna is pointing true West. The voltage between
pins 3 and 1 should equal 25% of X, and the meter should indicate 270
degrees.
3) Turn rotator until antenna is pointing true North. The voltage between
pins 3 and 1 should now equal 50% of X, and the meter should indicate 360 or
0 degrees.
4) Turn rotator until antenna is pointing true East. The voltage between
pins 3 and 1 should now equal 75% of X, and the meter should indicate 90
degrees.
This will tell you if the error is in the rotator or in the control box and
you can decide if the error is great enough to warrant replacement of the
rotator potentiometer ($28 last time I checked) or the meter movement.
----- Original Message -----
From: <K4BEV@aol.com>
To: <Towertalk@contesting.com>
Sent: Tuesday, November 19, 2002 1:08 PM
Subject: [Towertalk] How do you calibrate a CDE rotor?
> I have a CD45-II rotor, the control box is one with 3 levers (ccw, brake,
> cw), an on/off switch, and a calibrate pot.
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