Pitch Channel

TM 11-6625-646-15

through R104 to contacts of ROLL GYRO SIMULATOR

f. The 2.5-volt ac feedback component excitation

switch S101. Operating switch S101 to its two L or R

voltage from the SAS amplifier channel is connected to

positions connects phase-related operating voltages to

receptacle J60 pins c and e. From pins c and e the

SAS amplifier roll signal demodulator Q302 and limiter

excitation voltage is connected to the reference voltage

AR301. These voltages simulate the helicopter vgi roll

input of the actuator-simulator card at receptacle J65

signals.

pins 8 and 9. Here, the excitation voltage is used to

phase relate the operation of the SAS amplifier channel

1-16. Pitch Channel

(para 1-22). The excitation voltage is also connected to

(figs. 1-5 and 1-7)

the ac metering circuits through the PITCH (or ROLL)

The pitch channel test circuit measures the open and

FEEDBACK POT. EXCITATION position of FUNCTION

closed loop channel output of a SAS amplifier under

switch S7 (para 1-32).

test.

g. With adapter GAIN SWITCH S102 at AIR, the

a. The channel output signal is connected to

base of pitch gain control switch Q303 (in the SAS

receptacle J60 pins Y, Z, and a. From here the signal is

amplifier) is grounded through pins B of adapter

connected through receptacle J65 pins 2, 3 (dc

receptacle J101 and SAS amplifier receptacle J1. This

common), and 5 to the phase inverter stage of the

cuts off Q303 and provides full output of pitch rate gyro

actuator-simulator card. The differential output of the

RG1 as in SAS flight operation. With GAIN SWITCH

SAS amplifier channel at pins 2 and 5 is also connected

S102 at GRD, ground return is open and switch Q303

to jumpered pins 21 and 24 of receptacle J65. Only one

conducts shunting 40 percent of the pitch output as in

of these simulator card input circuits is active,

SAS ground operation.

depending on the mode of test set operation selected by

AXES METERS READ switch S4.

1-17. Yaw Channel

b. During open loop testing, the channel output is

(fig. 1-5)

routed directly through a meter multiplier resistor and

The yaw channel test circuit measures the open closed

relay contacts to the metering circuit output of the

loop channel output of a SAS amplifier under test.

actuator-simulator card at pins 20 and 2t of receptacle

J65.

a. The channel output signal is connected to pins

H, J, and K of receptacle J60. From here the signal is

c. During closed loop testing, the channel output is

connected through pins 2, 3 (dc common), and 5 of

converted to a positive or negative dc voltage, chopped,

receptacle J63 to the phase inverter stage of the

converted to a nominal sine wave, amplified, and fed

actuator-simulator card. The differential output of the

back to the SAS amplifier as a simulated feedback

SAS amplifier channel at pins 2 and 5 is also connected

signal (para 1-18 through 1-25).

This simulated

by jumper wires to pins 21 and 24 of receptacle J63.

feedback signal is also rectified on the actuator-

Only one of these actuator-simulator card input circuits

simulator card and connected through relay contacts to

is active, depending on the mode of test set operation

the metering circuit output at pins 20 and 23 of

selected by AXES METERS READ switch S4.

receptacle J65.

b. During open loop testing, the channel output is

d. The open or closed loop metering circuit from

routed directly through a meter multiplier resistor and

receptacle J65 pins 20 and 23 is routed to PITCH AXIS

relay contacts to the metering circuit output of the

meter M4 through adapter switch S5.

actuator-simulator card at pins 20 and 23 of receptacle

J63.

e. The feedback signal output from receptacle J65

pin 25 is routed to jumpered pins b and d of receptacle

c. During closed loop testing, the channel output is

J60. From this point, the signal is routed to the SAS

converted to a positive or negative

amplifier feedback (cancellation) circuits.