c. Diode switching is used to select one phase or the other from a 6. 3-volt center-tapped transformer
winding. Diodes CR8 and CR11 perform this function. When transistor 07 is turned on, one side of the 6. 3-volt
transformer winding is connected to ground by diode CR8. When transistor Q8 is turned on, the other side of the 6. 3-
volt transformer winding is connected to ground by diode CR11. Thus, the voltage at the centertap of the 6. 3-volt
transformer will reverse phase when Q7 and Q8 are alternately switched on. The voltage from the 6. 3-volt transformer
center tap is AC coupled by a capacitor Cl to scan control gain potentiometer R2.
d. The voltage picked up by the wiper of R2 is applied to azimuth servo amplifier AR2, as shown in
to control the speed
is scanned. The phase
of this voltage controls the direction
servo motor rotation. A level-set potentiometer, A1R8, is provided on the scan generator circuit card for initial alignment
of the circuits to set the voltage level of the collectors of transistors Q5 and Q6 at approximately 8.5 volts. The voltage
on the collectors of transistors Q5 and Q6 should be balanced for zero volt difference. Balancing can be accomplished
by adjusting the voltage from R4 to set the voltage on the collector of Q6 to the same level as the voltage on the
collector of Q5. When this is done, the sector width can be selected by adjusting R3. When scan control gain
potentiometer R2 is set to scan at the desired speed, the antenna will scan the preset arc at the desired speed.
(4) CONTROL INDICATOR TRANSMISSION ASSEMBLY - Figure 5-17 illustrates the gearing ratios and
arrangement for the synchros, drive motors, handwheels, digital counters, and, in the case of azimuth, scan clutch L3,
sector scan limit switch S8, and antenna position potentiometer R4. This diagram is self-explanatory.
C. ALIGNMENT AND ADJUSTMENT PROCEDURES - The only alignment and adjustment procedures which are to
be performed on the Control Indicator when not connected into the system is adjusting the sector scan clutch and limit
switch and zeroing the synchros. Synchro zeroing procedures are contained in paragraph 2 of this section. Additional in-
system adjustment procedures for the Control Indicator are contained in Section III of this manual.
(1) SCAN CLUTCH AND LIMIT SWITCH ADJUSTMENT
a. Manually rotate the azimuth and elevation gear trains until the TRUE AZIMUTH and TRUE ELEVATION
digital counters are at 0000.
b. Zero all synchros in accordance with the procedures set forth in paragraph 2 of this section.
Revised January 22, 1-" 8