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Drive System
Voltage and
Current Checks
Step 1
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Step 3
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• Visually inspect all mechanical parts for freedom of operation with no misalignment,
binding or interference. Check all cabling for sufficient slack to prevent cable strain as
well as adequate restraint to prevent abrasion or chaffing during antenna and feed
movement.
• Check security of antenna mounting and interconnecting assembly hardware. Be cer-
tain all electrical grounding connections (including cross-axis grounding straps) are
intact and secure, not corroded or broken. Thoroughly clean any noticeable corroded
portions of grounding cables, unplated portion of universal terminals and corresponding
mounting surfaces using a wire brush. Replace rather than tighten any loose A-325
structural hardware. The hardware distorts at initial installation and once loosened will
not maintain the required high strength friction connection. All other assembly and instal-
lation hardware should be tightened to its original torqued condition. When installing
new structural hardware, do not use a wrench with a lever arm longer than two feet.
• Examine painted aluminum and galvanized surfaces and tough-up where required.
At the conclusion of the installation procedure prior to turning the system over to the sta-
tion facility, an installation acceptance check off sheet was prepared and duly signed off
if installed by Andrew crew. Part of this check off included voltage readings retaken to
determine if proper voltage was available. Current readings were also taken as a refer-
ence for future comparison to serve as a troubleshooting aid in determining possible
equipment degradation and shortened life. Any current reading taken during the follow-
ing procedure that varies by more than five percent from the pre-established reference
values necessitates troubleshooting the particular system involved to determine the
cause and required corrective action.
Approximately every three months and during a period of down time, disconnect as
applicable the RF transmitter and all power supplies. The main disconnect switch in the
main load center box at the antenna site must be in the ON position and the
LOCAL/REMOTE switch in the local control motor drive controller must be in the LOCAL
position.
Open the outer local control/motor drive controller door at the antenna site to gain
access to the conductors supplying power to the azimuth, elevation, and polarization
drive motors.
NOTE: During the following procedures, the antenna drives (azimuth, elevation, and
polarization) will be powered to rotate the antenna and feed in both directions of travel.
Check that this condition can be tolerated from a safety as well as an operational stand-
point, and that the electrical limits are not reached before the testing is concluded.
Reaching an electrical limit before concluding a test necessitates rotating the antenna or
feed in the opposite direction a sufficient distance to permit retesting in the desired
direction.
Turn the FEED CCW/OFF/CW switch to either the CW or CCW position and while the
feed is rotating, carefully use a clamp on ammeter in accordance with the ammeter man-
ufacturer’s instructions to take current readings off each of the three conductors (phases)
connected to the load side of the polarization motor circuit breaker. Record the current
draw in the equipment log and compare the readings to the reference values entered in
Preventive Maintenance