TM 11-5840-281-35/1
RPM control R4059 is summed with the azimuth
AS-1291/TPN-8 and elevation drive motor B501 to
tachometer output in the electronic control pream- plifier
provide the two elevation scan sectors. Elevation drive
to provide the azimuth drive-control signal.
motor B501 is a 3-phase, 400-Hz, synchronous motor
(10) In the search mode, power is removed from
that is operated at either of two speeds. The motor shaft
the elevation drive motor. Antenna AS-1292/TPN-8 is
speed is determined by the mode of operation selected.
driven the same as in the simultaneous mode.
(2) In the NORM, 35 EL, and SIMULT modes,
(11) The electronic control amplifier provides the
elevation drive motor B501 is connected in a 12-pole
control voltage to the azimuth drive motor.
configuration and the shaft turns at approximately 3700
The electronic control amplifier consists of two
rpm. The motor shaft is coupled to the Antenna AS-
magnetic-amplifier circuits and four silicon-con- trolled
1291/TPN-8 crank through reduction gears to drive the
rectifiers. The magnetic amplifiers receive the error
elevation crank at 30 rpm. Antenna AS-1291/TPN-8 has
current from the electronic control preamplifier and
one up look and one down look for each revolution of
produce turn-on gates which are used to switch the
the crank; consequently, there are 60 elevation looks-
silicon-controlled rectifiers into conduction. The duration
per-minute.
of the turn-on gates and the amount of power delivered
(3) In the 60 AZ mode, elevation drive motor
to the azimuth drive motor are functions of the
B501 is connected in a 24-pole configuration, reducing
magnitude of the error current.
the shaft speed by half (or 1850 rpm) and reducing the
(12) The current polarity determines which
scan rate to 30 Iooks-per minute. The reduced scan rate
magnetic amplifier develops the gates. When the error
is necessary to allow Antenna AS-1292/TPN-8
current polarity is such that the no. 1 magnetic amplifier
additional time to cover its increased scan sector in the
circuit develops the gates, phase A of the 400-Hz power
60 AZ mode.
is switched through two silicon-controlled rectifiers to
(4) The elevation actuator assembly positions
motor control no. 1 winding of the azimuth drive motor,
the elevation crank push rod connection on Antenna AS-
driving the motor in a cw direction. An error current of
1291/TPN-8 to produce either the 10- degree or 35-
opposite polarity cuts off the no. 1 magnetic amplifier
degree scan angles. The elevation actuator motor is a
circuit and causes the no. 2 magnetic amplifier circuit to
dc motor with two opposite- wound field windings. The
develop turn-on gates. The trn-on gates applied to two
motor direction is con- trolled by exciting either one
silicon-controlled rectifiers switch phase A of the 400-Hz
winding or the other. When +28 volts is applied to the 3-
power to motor-control no.
degree el scan winding, the motor retracts the actuator.
2 winding, and cause the azimuth drive motor to rotate
Switch S504 opens to remove the dc voltage when the
in the opposite direction. A bias supply in the amplifier
actuator is in the proper position. The total travel of
provides the bias currents for both no. 1 and no. 2
Antenna AS-1291/TPN-8 in the 35-degree configuration
magnetic amplifiers.
is from --19 to +61 degrees (36-degree scan sector and
b. Antenna Drive TG-114/TPN-8 Circuit (Fig.
44 degrees of over- scan). When Radar Set AN/TPN-18
7-8). Antenna Drive TG-114/TPN-8 assembly performs
is placed in either the NORM, 60" AZ, or SIMULT mode,
the following functions: provides driving power for
+28 volts is applied to the 10-degree el scan winding of
Antenna AS-1291/TPN-8; provides a synchronizing
the actuator motor, causing the actuator to extend.
voltage for Antenna AS-1292/TPN-8 during all precision
Switch S505 removes the +28 volts when the actuator is
modes; provides a dc voltage proportional to the antenna
in position. The total antenna travel in the 10-degree
scan angle to the circuits of the control-indicator section;
configuration is from +22 to --6.5 degrees.
and, by means of cam-operated micro- switches,
(5) The 10-degree el and 35-degree el synchro
provides gates to Remote Switching Control C-
units B502 and B503 are geared to the elevation crank at
6989/TPN-18 to unblank the display during the 10-
a 1:1 ratio; thus, for one full turn of the crank, each
degree and 35-degree scan periods; and provides gates
synchro rotor completes one turn. Both synchro rotors
to blank the azimuth display during elevation scan in
are excited by the C- phase of the 400-Hz power;
SIMULT operation.
however, only one output is utilized at a time. In the
(1) An actuator assembly associated with
NORM and 60 AZ modes, the output of 10-degree el
Antenna Drive TG-114/TPN-8 assembly adjusts the
synchro
mechanical linkage between Antenna
2-24
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