Raytheon Pathfinder 1200 Instruction Manual page 86

14) Parallel/Serial Converter
The four bits parallel data of the video RAM output is fed to the four bits shift
resistor IC62 D4 to D1 input and latched by the mode control pulse on IC62-6.
The serial video pulse appears on Q4 IC62-10 clocked by the 6 MHz clock input
pulse on IC62-8/9.
15) Bearing Pulse Generator
The signal of the motor-encoder in the scanner unit is fed to the schmitt trigger
IC34-ll via a filter of C25 and R51 and shaped into a suitable trigger pulse. The
...
IC34-10 output is then fed to IC78 (monostable multivibrator) IC78-5 produces an
approximately 700
usee
pulse IC78-5 output is fed to IC35 and synchronized ,to
the display timing. At the same time IC35 is controlled by the OPERATE signal that
is the output of AND gate IC80-3. IC80-1 input is the 90 seconds timer output.
IC80-2 input is OPERATE switch signal of which timing is synchronized to display
vertical timing by IC79.
16) Main Trigger Generator
The IC35-6 output is fed to the main trigger generator IC21 via a differential
circuit made up of C65, R78 and R79. IC2l-l3 produces an approximately 10 usee
main trigger pulse which is controlled by a HOLD signal from IC80-6. The main
trigger pulse stops whenever the HOLD switch is pushed, or for approximately 0.5
second during changes of the transmitter pulse width. IC4l-6 and IC78-4 produce
the 0.5 second pulse from the pulse width control signal when the RANGE switch
is changed.
17) Transmitter Trigger Generator
The trailing edge of the pulse from IC2l-13 is differentiated by C20 and R43
is amplified by TR 12 and TR 12-C output is fed to TR 11. TR 11 is an emitter follower
and drives the modulator.
18) Delay Circuit (0 nm adjust)
The delay circuit consists of R46, RV3, C22 and IC34-8 and compensates for
the delay time between transmitter triggering and firing by adjusting RV3 so that
received video appears on the display at its proper range.
19) Gain STC (Sea Clutter) Circuit
R3
12 V
-------I/INY-......- .......... - - - - - - - - - - - - - - - - - - ,
mmz7.1~
l.r
R6
Vsl
TR2
- t- Vs2
C6
R9
GS ourpof
6·20
FIG. 6-7 GAIN - STC CIRCUIT