Technical data

Preventive Maintenance

Drive System

Voltage and

Current Checks

Step 1

Step 2

Step 3

Step 4

• Check security of antenna mounting and interconnecting assembly hardware. Be

certain all electrical grounding connections (including cross-axis grounding straps)

and 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 with 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 installation 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 touch-up where required.

At the conclusion of the installation procedure and prior to turning the system over to the

station facility, an installation acceptance check-off sheet was prepared and duly signed off

if installed by an 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 reference

for future comparison to serve as a troubleshooting aid in determining possible equipment

degradation and shortened life. Any current reading taken during the following procedure

that signiﬁcantly varies by more than ﬁve percent from the preestablished reference values

necessitates trouble shooting 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 detachable

hand-held controller assembly must be plugged in.

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. Turn the primary power disconnect switch to the ON position.

Turn the Az/El speed switch to the FAST position. Turn the AZIMUTH EAST/WEST

switch to either position and while the antenna is rotating, carefully use a clamp-on

ammeter in accordance with the ammeter manufacturer’s instructions to take current

readings off each of the power conductors (phases) connected to the main terminal

block at the bottom of the panel. Record the current draw in the equipment log and compare

the readings to the reference values entered in the installation/acceptance checkoff.

If the readings differ signiﬁcantly, refer to the appropriate troubleshooting information

and perform the 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 preceding step (3) with the AZIMUTH EAST/WEST switch in the alternate operating

position.