Position the actuator to its center position.
Connect an ohmmeter from pin H to pin A on connector P1.
Loosen the screws holding the potentiometer in position and rotate the potentiometer until the
Tighten the screws loosened in step (3).
WIRING DIAGRAM AND PARTS LIST - Figure 5-5 is a wiring diagram of the electromechanical linear
actuator. The parts list is contained in Table 5-6.
ANTENNA PEDESTAL (See Figure 5-6) A. GENERAL DESCRIPTION AND THEORY OF OPERATION - The
antenna pedestal used with the Antenna System consists of a cylindrical riser base (item 7) which houses the azimuth
servo drive assembly (item 1), azimuth electric pressure brake, and motor control units (items 10 and 11).
The azimuth servo drive assembly consists of an AC servo motor and a gear train connected to a
vertical tubular shaft mounted in a precision bearing assembly. This assembly has a mounting flange on top for
mounting the antenna mast. An angle scale, which is graduated from 0 to 360 degrees and attached to the vertical
tubular shaft and two index markers, one at zero and one 180 degrees, attached to the stable part of the riser base,
provides a visual indication of the pedestal's azimuth rotation. An azimuth synchro assembly which contains two
synchros, two rotary electrical limit switches, a resolver, and a cable-wrap potentiometer is also geared to the azimuth
drive motor. The synchros provide control and data signals for the azimuth axis. The resolver provides position
information to the display scope. The electrical limit switches limit rotation of the azimuth axis to 270 degrees. The
limit switches engage 30 degrees before mechanical stops in the azimuth drive assembly and act as a buffer for the
mechanical stops. The detailed theory of operation for the synchros is contained in paragraph 2 of this section. The
theory of synchros, cable-wrap potentiometer and limit switches as used in the Antenna System is contained in Section I.
The azimuth electric pressure brake in the azimuth drive assembly is a solenoid-operated brake which engages any time
power is removed from the antenna pedestal. With the pedestal deenergized, the brake may be manually released by
rotating the release knob in a clockwise direction as shown on Figure 5-7.