external source and produces varying output voltages from the rotor winding. The output voltage of the control
transformer can be varied either by displacement of the rotor or by varying the input data signal applied to the stator
input from the associated control transformer.
DIFFERENTIAL CONTROL TRANSMITTERS - The differential control transmitters used in the
Antenna System connect the stators of control transmitters to the stators of control transformers so that the rotation of
any one shaft is either the sum of or the difference between the rotation of the other two. Both the rotor and stator
winding of the differential control transmitters consist of three Y-connected coils. The stator of the differential receives its
excitation from the stator of a control transmitter. The voltages appearing across the rotor terminals of the differential
are determined by the magnetic field produced by the stator currents and the physical position of the rotor. The magnetic
field created by the stator currents assumes an angle corresponding to that of the magnetic field in the transmitter
supplying the excitation. If the rotor position changes, the voltage present at the rotor terminals changes.
SYNCHRO ZEROING PROCEDURES - Synchros are factory adjusted to electrical zero at zero-degree
azimuth and elevation. The following procedure should be followed to rezero the synchros if the factory adjustments
have been altered.
Before zeroing the synchros on the elevation drive assembly and antenna pedestal, set the
elevation and azimuth angles to zero as read on their respective angle dials. This will place the
azimuth angle in the center of its travel, midway between the limit stops, and the elevation angle
will correspond to horizon pointing.
CONTROL AND TORQUE TRANSMITTER
Loosen the clamps holding the synchro transmitter in place sufficiently to permit rotating the
synchro by hand with moderate force. Disconnect the external wiring to the stator terminals.
Connect a jumper between rotor terminal R2 and stator terminal S3.
Connect a voltmeter between rotor terminal R1 and stator terminal S2. Set the voltmeter to its
0- to 250-volt scale.
Energize the rotor of the synchro transmitter from a 115-volt, 60-cycle a-c source.