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Delrin bushings and shoulder bolts as pivot fasteners. Position feedback is generated with similar
sensors as used on the Az and El axis.
7.2.3.1
Polarization Drive
The feed/polarization drive can found underneath the pol mounting plate. The actual arrangement
is model dependent. The worm gear on the feed horn extends through a slot and mates with the
drive worm gear. The polarization drive gear is adjusted to allow minimal backlash to the worm gear
mounted on the feed horn. The polarization drive motor is a DC type with shaft encoder. A hex
adaptor on the worm shaft provides manual polarization of the feed assembly using the hand crank
in the case of a drive failure.
Figure 7.2.3.1 - Feed and Polarization Drive
Since the low backlash worm gear drive isolates the feed from the motor, no brake is required. No
maintenance of the polarization motor/assembly is required.
7.2.3.2
Potentiometer (POT)
The polarization position feedback is typically produced by a potentiometer. The pot is an adjustable
voltage divider using a three-terminal resistor with a sliding contact. The pot is driven by the output
shaft of the worm gear drive. The potentiometer is sealed and rated for IP 65 environment - wind,
rain, dust, etc. The potentiometer is mechanically centered at the travel position when the Pol
platform is in the physical center position. Limits are controlled by using inputs from the
potentiometer and / or encoder together and are set in, and controlled by, the AAQ controller.
BUC
Hex Adaptor
Pol Drive
LNB
Ortho Mode
Transducer
Feed Horn