TM 11-5840-281-35/1
(19) Rotate OUTPUT ATTEN. control to de-
(33) Disconnect oscilloscope CHANNEL A
crease attenuation until OUTPUT ATTEN. control dial
INPUT test prod from Intermediate Frequency Amplifier
setting is 10 dbm less than that noted in (18) above.
AF-3339/TPN-8 and connect to SUM GAIN testpoint
Record OUTPUT ATTEN. control dial setting.
TP3902 on stc unit.
(20) On oscilloscope, adjust CHANNEL A
(34) On oscilloscope, adjust CHANNEL A
SENSITIVITY and CHANNEL A SENSITIV- ITY
SENSITIVITY and CHANNEL A SENSITIVITY VERNIER
VERNIER controls to obtain pulse amplitude of 1.0 cm
controls until stc waveform is 2 cm in amplitude.
on oscilloscope.
(35) Disconnect oscilloscope CHANNEL A
(21) On stc unit, rotate STC SLOPE control
INPUT test prod from SUM GAIN testpoint TP3902 and
R3911 cw until pulse amplitude on oscilloscope just
connect to DIFF GAIN testpoint TP3903.
begins to decrease.
(36) On stc unit, adjust DIFF STC GAIN
(22) On radar test set, set OUTPUT
control R3914 until stc waveform is 1.0 cm in amplitude.
ATTEN. controls dial (rotate cw) to 20 dbm less than
(37) Disconnect oscilloscope and radar test
setting recorded in (19) above.
set.
(23) Adjust PULSE DELAY control on radar
(38) Replace front and rear covers on
test set and SUM STC GAIN control R3913 on stc unit
Radar Receiver-Transmitter RT-818/TPN-18 and secure
until pulse on oscilloscope appears at 30 microseconds
with fasteners.
after pretrigger time.
(24) On stc unit, adjust SUM STC GAIN
3-36. Control-Indicator C-6988/TPN-18 Dc Voltage
control R3913 until pulse amplitude on oscilloscope is
Supply Adjustments
again 1.0 cm in amplitude.
(25) On radar test set, adjust PULSE
Refer to TM 11-5840-281-12 for Control-Indicator C-
DELAY control until pulse appears 120 microseconds
6988/TPN-18 dc voltage supply adjustments.
after pretrigger.
(26) Set OUTPUT ATTEN. control dial to
3-37. Angle Volts Control Calibration
setting recorded ii (i9) above.
(27) on STC unit, adjust STC SLOPE
control R3911 until pulse on oscilloscope is 1.0 cm in
a. Test Equipment Required.
Clinometer
amplitude.
MP3502 (clinometer).
(28) On radar test set, set OUTPUT
ATTEN. control dial to 20 dbm less than indication
b. Equipment Conditions.
recorded in (19) above.
(1) Radar Set AN/TPN-18 turned on.
(29) Adjust PULSE DELAY control on radar
(2) Radar set group must be level.
test set and SUM STC GAIN control R3913 on stc unit
(3) Elevation angle data potentiometer and
until pulse on oscilloscope appears at 30 microseconds
electronic filter must be aligned (para 3-21).
after pretrigger time.
(4) Azimuth angle data potentiometer and
(30) Observe that pulse on oscilloscope is
electronic filter must be aligned (para 3-24).
1.0 cm in amplitude. If pulse is not 1.0 cm in amplitude,
(5) On Radar Receiver-Transmitter RT-818/
adjust SUM STC GAIN control R3913 on stc unit until
TPN-18 control panel, SCAN and HV switches placed to
pulse amplitude is 1.0 cm.
OFF.
(31) If SUM STC GAIN control R3913
(6) On master Control-Indicator C-6988/
required adjustment in (30) above, repeat steps (25)
TPN-18 and Pulse Generator 0-1333/TPN-18, SCAN
through (30) above until no further adjustment of STC
MODE switch placed to NORM, SCAN and
SLOPE control R3911 and SUM STC GAIN control
TRANSMITTER switches OFF, and ANGLE VOLTS
R3913 is required.
switch placed to EL
(32) Position elevation Antenna AS-1291/
TPN-8 by hand to approximately midscan. On master
Pulse Generator "O-1333/TPN-18, place SCAN MODE
switch to NORM position. Maintain midscan while
performing (33) through (36) below.
3-46
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