CE-1008
This output is applied to a servoamplifier AR2 in the Control Indicator which is identical to the servoamplifier in the
antenna pedestal. The output of the servoamplifier drives motor MG1 in the Control Indicator, which is coupled through
a gear train to the true azimuth counter and to slave control transformer B1. Thus, the slave control transformer B1 is
driven to null the error output on its stator leads and the true azimuth counter is driven to indicate the azimuth position of
the antenna. Servoamplifier AR2 receives 115-volts AC from relay K3 in the Power Supply, which is energized by 28-
volts DC through contacts of the MODE SELECT switch on the Control Indicator.
(4) SCAN MODE OF OPERATION - In the scan mode of operation, the antenna is automatically
repositioned in azimuth by a positioning voltage from a scan generator in the Control Indicator. This mode of operation
allows any preset sector in azimuth within a maximum sector of 270 degrees, with reference to the system's zero
reference point, to be automatically scanned. In this mode, the elevation channel is controlled by the manually operated
handwheel on the front panel of the Control Indicator in the same manner as the manual mode of operation.
a.
CONTROL SECTOR potentiometer, R2, and the SCAN CONTROL GAIN potentiometer, R3, on the front panel of the
Control Indicator and the antenna position potentiometer, R4, which is coupled through a magnetic clutch to the gear
train driven by the azimuth drive motor. Potentiometer R2 controls the width of the sector to be scanned. Potentiometer
R3 controls the gain of the error output and, subsequently, the rate at which the sector is scanned. Potentiometer R4 is a
continuous rotation potentiometer which is spring loaded to its center position. This potentiometer is connected through a
magnetic clutch, L3, when the clutch is energized, to the azimuth gear train in the Control Indicator driven by the drive
motor MG1 and follows the gear train from its position when the clutch was energized. When the scan clutch is
deenergized, potentiometer R4 returns to its center position through the spring loading action. The output of R4 is,
therefore, an analog voltage which is proportional to the azimuth angle of the antenna, relative to the position of the
antenna prior to scan clutch engagement. Operation of this circuit is as follows:
b.
With the MODE SELECT switch, S2, in the SCAN position, 28-volts DC is applied through scan
limit switch S8 to energize scan clutch, L3, connecting potentiometer R4 to the azimuth gear train. The output of R4 is
an analog voltage which is proportional to the antenna position around the angle to be scanned. A 2: 1 voltage divider,
formed by R6, R9, R11 and R12, is connected between the arm of the potentiometer R4 and SCAN CONTROL SECTOR
width potentiometer R2. Differential amplifier Al senses the voltage difference between the voltage divider and the arm
of potentiometer R2. The outputs of Al are applied to two emitter-follower amplifiers, A2 and A3, which act as a buffer to
prevent differential amplifier A4 from loading Al. The outputs of A4
Revised January 22, 1968
1-16
Previous Page
