TM 11-5821-284-34
above the threshold of CR10 or CR9), the rotation logic
The sequential pulsing logic circuit provides a square-
remains on and the sequential pulsing logic remains
wave output to step the 3-state ring counter used for
engaged. When this occurs, the sequential pulsing logic
motor sequencing, provides a gating pulse to the
free runs providing gating pulses and sequence timing
operational amplifier, and provides an external indication.
pulses at a rate of 500 Hz.
When the output of the operational amplifier is above the
2-6.
Servo Rotation Logic Circuits Analysis
threshold of CR9 or below the threshold of CR10, a logic
"O" is supplied to NAND gate A4C on pin 11 or 13. With
The servo rotation logic provides a signal to start the
a logic "0" input, A4C provides a logic "1" to pin 13 of
sequential pulsing logic circuit, is enabled/inhibited by the
A3D. Inverter A3D supplies a logic "O" to Q7 base,
RF on circuit, detects the polarization of signals from the
biasing Q7 off. With Q7 biased off, a positive potential is
operational amplifier AR1, and provides a signal to the
applied to permit the free-running multivibrator Q8 and
servo motor sequencing logic that determines the
Q9 to supply 500-Hz square-wave output pulses to the
direction of rotation of the servo motor when tuning is
three circuits mentioned above. However, if the gating
required and also provides a hold signal when RF power
pulse to the operational amplifier places its out-put
is not applied.
between the thresholds of CR9 and CR10, the sequential
a. With RF transmit power applied to the
pulsing logic will be held in its "off" state until the voltage
at the operational amplifier output again passes the
antenna, a logic "1" is supplied by the RF-on circuit to
threshold of either CR9 or CR10 This provides a control
enable NAND gates A4A and A4B. If tuning is required,
in the out-put frequency of the free-running multivibrator
a signal of less than +3.9 volts dc or greater than +8.2
to control the speed of the servo motor.
volts dc is supplied by the operational amplifier to the
input of the servo rotation logic.
b. When the output of AR1 decreases to
2-8.
Servo Motor Sequencing Logic Analysis
below +3.9 volts dc, CR10 biases off, Q11 biases off,
and Q12 conducts to supply a logic "O" to A4B-8. With
The servo motor sequencing logic is a 3-state ring
CR10 biased off, CR9 will also be biased off and Q14
counter with three NAND gate outputs to provide the
biases off to supply a logic "1" to A4A-1. With a logic "O"
signals required for energizing the tuning motor.
at A4B-8, A4B has a logic "1" output and A5B has a logic
a. Flip-flops Al and A2 are JKLM flip-flops.
"0" output. With a logic "1" at A4A-1, a logic "1" at A4A-
When the 1 to 0 transition of a pulse applied at the C
2, and a logic "1" at A4A-3 (supplied by A4B), A4A has a
(clock) terminal occurs, the output state of the flip-flops
logic "0" output, and A5A has a logic "1" output. The
will change except as follows: When a logic "O" is
counter-clockwise (ccw) rotation of the servo motor is
supplied on a J and an L terminal, the flip-flop is inhibited
initiated to increase antenna capacitance.
from being set, and when a logic "O" is supplied on a K
c. When the output of AR1 increases to above
and an M terminal, the flip-flop is inhibited from being
+8 2 volts dc, CR9 conducts, Q14 conducts, and a logic
reset. When a logic "O" is supplied by A5A-3 and A5B-7,
"O" is supplied to A4A-1. With CR9 con-ducting, CR10
the servo motor sequencing logic will, provide a hold
will also conduct, Q11 conducts, and Q12 biases off to
signal, and Al and A2 will not change states. Al and A2
supply a logic "1" to A4B-8. With a logic "O" at A4A-1,
will be locked in the state they were in when the last
A4A has a logic "1" output and A5A has a logic "0"
pulse was received. b When a logic "O" is supplied by
output. With a logic "1" at A4B-8, a logic "1" at A4B-7,
A5A-3 and a , logic "1" is supplied by A5B-7, a clockwise
and a logic "1" at A4B-6 (supplied by A4A), A4B has a
rotation of the servo motor is initiated and the servo
logic "0" output, and A5B has a logic "1" out-put. The
motor will rotate 15 degrees with each sequence timing
clockwise (cw) rotation of the servo motor is initiated to
pulse received. The faster the sequence timing pulses
decrease antenna capacitance.
are received, the faster the servo motor will rotate. Refer
d. When either cw or ccw rotation is initiated, a
to d and f (below) For the servo motor sequencing logic
logic "O" is supplied to the sequential pulsing logic circuit.
truth tables for clockwise rotation.
2-7.
Sequential Pulsing Logic Analysis (fig. 2-6)
2-6
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