2.6 DISCRIMINATORS 
The alignment and maintenance of the discriminators is fully described in the manufac- 
turer’s literature.© It should be noted that if tubes in the frequency selective circuitry are 
changed, the linearity will probably be affected. 
3. CONTROL EQUIPMENT 
3.1 RUDDER CHANNEL 
3.1.1 Rudder Control Panel 
The three types of rudder controls are used in a voltage divider network of the 
rudder channel subcarrier oscillator. To switch from one type of control to another without 
recalibration, the controls must be matched to about + 0.1 percent for equal end resistance 
and for total resistance. If any component has to be replaced, the entire circuit should be 
checked and retrimmed, if necessary. 
3.1.2 Subcarrier Circuits 
Adjust the subcarrier oscillators as described in Section IV, 2.1.1. Adjust the front 
panel controls of the discriminator as described in the calibrating procedure, Section III, 2.2.1. 
If internal discriminator adjustments are required, they should be made in accordance with 
procedures described in Reference 6. 
3.1.3 Rudder Servo 
The adjustments to the rudder servo should be made in the following order; however, 
steps may be omitted if it is felt that only certain controls require adjustment: 
a. With the power turned OFF, mechanically position the rudder servo control 
potentiometer so that the slider is at the center of its range when the digital indicator on the 
servo ig at zero. 
b. Adjust the cams for the limit switch (Figure 44) so that the switch opens at 
+ 47 degrees or at smaller angles if rudder throw is limited. 
ce. Connect the servo unit to the amplifier and set the circuit selector to the 
WIRE CONTROL, VELOCITY position. Connect a 5000-ohm multiturn potentiometer to the 
input circuit for position control. See Figure 42 for connections. 
d. Disconnect the jumper shown in Figure 41 to remove servo motor power. 
e. Connect an oscilloscope to one of the terminals marked G on the A-19 
transformer. 
IV-4 
