Andrew 3.7-Meter Earth Station Antenna - Manual (Page 83)

Step 4
Step 5
Step 6
Step 7
Step 8
Step 9
Pedestal Mount
Bearing Pad
Adjustment
Step 1
Step 2
Step 3
Step 4
Step 5
83
Repeat preceding step (3) with the FEED CCW/OFF/CW switch in the alternate operat-
ing position.
Turn the AZIMUTH EAST/WEST switch to either position and while the antenna is rotat-
ing, carefully use a clamp on ammeter in accordance with the ammeter manufacturer’s
instructions to take current readings off each of the three conductors (phases) connect-
ed to the load side of the azimuth drive motor circuit breaker. Record the current draw in
the equipment log and compare the readings to the reference values entered in the
installation/acceptance check off. If the readings differ by more than five percent, refer to
appropriate troubleshooting information and perform applicable corrective action. Then
take voltage readings off each of the three conductors; the readings should agree with
each other—within two percent. Turn the AZIMUTH switch to OFF.
Repeat steps (5) with the AZIMUTH EAST/WEST switch in the alternate operating posi-
tion.
Turn the ELEVATION DOWN/UP switch to either position and while the antenna is rotat-
ing, carefully use a clamp on ammeter in accordance with the ammeter manufacturer’s
instructions to take current readings off each of the three conductors (phases) connect-
ed to the load side of the elevation drive motor circuit breaker. Record the current draw
in the equipment log and compare the readings to the reference values entered in the
installation/acceptance check off. If the readings differ by more than five percent, refer to
appropriate troubleshooting information and perform applicable corrective action. Then
take voltage readings off each of the three conductors; the readings should agree with
each other within two percent. Turn the ELEVATION switch to OFF.
Repeat steps (7) with the ELEVATION DOWN/UP switch in the alternate operating posi-
tion.
If all voltage and current readings are within tolerance, close the local control/motor
drive controller inner door and place the LOCAL/REMOTE switch in the REMOTE posi-
tion to return antenna control to the studio. Then close and lock the outer local
control/motor drive controller door.
The bearing pad (within the pedestal mount) adjustment rods/bolts require yearly adjust-
ment and verification of torque value. With the antenna at zenith (90 degrees), follow
the procedures presented below:
Loosen jam nuts on all adjustment rods/bolts.
Torque the upper adjustment rod evenly to 40 - 45 foot-pounds. Then torque the lower
adjustment rod evenly to 40 - 45 foot-pounds.
Torque the upper adjustment bolt evenly to 40 - 45 foot-pounds. Then torque the lower
adjustment bolt evenly to 40 - 45 foot-pounds.
Repeat steps 2 and 3 verifying all adjustment rods/bolts are evenly torqued within the
limits specified.
Tighten the jam nuts.
Preventive Maintenance