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3.5 AZIMUTH POSITION FEEDBACK
The azimuth position feedback is produced by a 10 turn, 1K-ohm potentiometer driven by a gear located on
kingpin post . (Fig. Below) Since the Roto-Lok drive has no backlash, the position feedback is as accurate (1%)
as the resolution (.3°) and accuracy of the potentiometer and the backlash between the potentiometer and the
azimuth capstan. The potentiometer is sealed and rated for IP 65 environment - wind, rain, dust, etc.
The potentiometer is mounted on AZ/EL casting. The azimuth potentiometer is slotted and driven by a belt and a
small sprocket located on the AZ king pin and the small gear on the potentiometer. The potentiometer is mechani-
cally centered at the travel position (5 turns from either end) when AZ platform is in the AZ stow position. This is
accomplished by removing the belt from the potentiometer gear. The potentiometer may also be electrically
zeroed by the controller. See pertaining section of the controller manual.
3.6 AZIMUTH STOW AND LIMIT SWITCHES
The controller uses the AZ potentiometer voltage to determine limits. Therefore, the positioner is equipped with
only an azimuth stow position switch.
The azimuth stow limit switch is mounted on the AZ/EL casting, on a boss next to azimuth drive sprocket. ( Fig.
Below) The switch is fixed relative to the mounting surface and is actuated by a small shoulder bolt located on the
azimuth potentiometer drive sprocket. The stow switch actuation occurs at slightly different positions depending if
you approach the stow position from CW or CCW. Therefore, the azimuth stow position will vary approximately 1º
from stowing from CW or CCW.
Since the controller drives to 0° AZ after sensing
the stow switch, the AZ stow position can be varied
by either changing the zero position of the AZ
potentiometer or zero voltage of the controller.
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