Dawn CONTROL-1500A Manual page 26

CONTROL-1500A Single Axis Antenna Controller
2. Connect an ohm meter between the wiper of the pot (terminal 2 on the Spectrol or
Contelec) and one of the other two terminals. Note that when the shaft position of the pot
is near one of the pot's mechanical limits, the ohm meter will read either less than 25 ohms,
or the value found in step 1.
3. With a bench power supply, automobile battery charger, or some other voltage source,
carefully apply power to the feed's DC motor to move it towards one mechanical limit or the
other. (Note that the feed motor for the Seavey feed nominally requires 24 volts DC at
approximately 150 mA. The feed motor should move with an applied voltage of 6 to 12
volts DC.)
4. While movement is in progress, monitor the ohm meter to insure that the pot's mechanical
limit is not reached. If the ohm meter indicates that the pot's mechanical limit is being
approached, quickly disconnect the power source and perform the procedure outlined in
the section entitled "Centering the Pot".
5. If the feed can safely move to one of its mechanical limits, reverse the power supply leads
and move the pot towards the other mechanical limit. Once again, monitor the ohm meter
to insure that the pot's mechanical limits are not exceeded. If the feed cannot be moved to
its mechanical limit without approaching the pot's mechanical limit, perform the procedure
outlined in the following paragraphs.
Centering the Pot
The procedure outlined here may be used to center the feed's range of travel within the pot's
mechanical limits.
1. Find the total resistance of the pot. See step (1) above.
2. Loosen up the allen screw which holds the shaft of the pot to the gear.
3. Apply power to the feed motor (as in step (3) above) to center the feed in the middle of its
range of travel. As the feed rotates, make sure that the shaft of the pot does not turn.
4. When the feed has been centered in its range of travel, connect the ohm meter between
the wiper and one of the other terminals of the pot. Rotate the shaft of the pot until the
resistance read from the ohm meter is one half of the value of the pot's total resistance
(obtained in step (1)).
5. Tighten the allen screw and verify that the pot is properly centered by performing the
procedure outlined earlier in this section.
3.3.3.2 Connecting the CONTROL-1500 to the Rotating Feed
To configure the CONTROL-1500 software to work with the RC2KPOL daughterboard, the
controller's 24 VDC Rot Feed CONFIG mode item should be set to 1-Yes.
Figure 3.4 documents the interface of the CONTROL-1500 to the rotating feed. Two sets of
electrical connections are required to interface an CONTROL-1500 equipped with the RC2KPOL
option to the rotating feed device. Two conductors are required for the DC motor drive and a shielded
triple with bare drain wire is required to interface the potentiometer. The drain wire of the shielded
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Chapter 3 Installation/Setup 19