Raytheon Pathfinder 1200 Instruction Manual page 87

ICl-l is a voltage follower of GAIN control, ICl-7 is a voltage follower of
STC control. With the SEA CLUTTER control fully counterclockwise, Vs is equal to
VG. Consequently, the de output voltage of GAIN control appears on TR2-E (GS
output) via R6, Rll, R7 and TR2. GS output voltage variation is approximately 5 V
to 9V. When GS output voltage is 5V, the IF gain is highest.
When the Sea Clutter Control is clockwise, and the negative going pulse from
the delay circuit is fed to TR 1-B, TR 1 turns on. Therefore, C5 will be charged up to
a.yoltage determined by VS, VG and the ratio of Rll and R6. After the GS pulse
is over, TR 1 turns off and VGs changes from Vs to Vs
1
and CS begins to discharge
via R6, Rll and RIO. When VGs reaches VS2, CD2 goes into cut off, then CS con-
tinues to discharge via R6 until VGs becomes equal to VG. GS output is filtered in
the receiver unit and fed to the IF amplifier.
GS pulse
1-----1------ - - -- - -- - - - --
Vs
STC control voltage
VSl
STC waveform
--''"'''''==-----
VS2
\
Max. GAIN
level
Varied
by
GAIN
cont,
GAIN control voltage (VG)
----------
Max. STC level
,
t, ..... _
\":---------1
"-
----------,
" -
Voltage
variation
FIG. 6-8 GAIN - STC WAVEFORM
6-21