TM 11-5840-281-35/1
b. Equipment Conditions and Connections.
(i) CHANNEL A AC-DC: AC.
(j)
CHANNEL
A
SENSITIVITY
(1) Radar Set AN/TPN-18 turned on and
(VOLTS/CM): .2.
front and rear covers of Radar Receiver-Transmitter RT-
(k) CHANNEL A SENSITIVITY VER-
18/TPN-18 removed for access to controls.
NIER: CALIBRATED.
(2) On master Control-Indicator C-6988/
(l) CHANNEL A POLARITY: + UP.
TPN-18 and Pulse Generator O-1333/TPN-18, SCAN
(7) On Radar Receiver-Transmitter RT-
MODE switch placed to SEARCH, SCAN switch OFF,
818/TPN-18 control panel, adjust LO FREQ ADJ until
TRANSMITTER switch placed to OFF, then to WIDE, HV
video signals appear on oscilloscope. If necessary,
ON indicator extinguished, STC switch placed to OFF,
readjust LO ATTEN control for 0.6- ma indication on
and IF GAIN-AZ control fully cw.
XTAL CUR meter.
(3) Test equipment connected as shown in
(8) On oscilloscope, adjust HORIZONTAL
c. Procedure.
DISPLAY EXTERNAL VERNIER, SWEEP TIME
VERNIER, and CHANNEL A SENSI- TIVITY VERNIER
(1) On vtvm, place RANGE switch to 30V
to obtain optimum display of medium-range radar
and SELECTOR switch to (-).
returns.
(2) Check vtvm indication. Vtvm should
(9) Adjust LO TUNE control for maximum
indicate approximately little or no voltage. If not, ad- just
indication on XTAL CUR meter. If necessary, readjust
MAX SENS control R4079 on Remote Switching Control
LO ATTEN control for 0.6-ma indication on XTAL CUR
C-6989/TPN-18 slowly cw until vtvm indicates 0 vdc. Do
meter.
not adjust MAX SENS control R4079 any further in cw
direction than is required.
(3) Disconnect vtvm DC lead from SUM
NOTE
GAIN testpoint TP3902.
(4) On vtvm, place SELECTOR switch to
Adjust IF GAIN-AZ control on master Control-
(+) and connect DC lead to IAGC PULSE test- point
Indicator C-6988/TPN-18 to maintain applicable
TP302 on Intermediate Frequency Amplifier AM-
radar returns below limiting level while aligning
3339/TPN-8.
local oscillator in step (10) below.
(5) On Intermediate Frequency Amplifier
AM-8339/TPN-8, adjust IAGC ADJ control R350 until
(10) Alternately adjust LO FREQ ADJ
vtvm indicates +1.5 volts.
for maximum amplitude of a medium range video signal
(6) Disconnect vtvm.
on oscilloscope and adjust LO TUNE control for
(7) On oscilloscope, place controls to
maximum XTAL CUR meter indication until video signal
positions indicated in (a) through (k) below.
and XTAL CUR meter indication are simultaneously at
(a) POWER: ON.
maximum.
(b) SWEEP MODE: PRESET.
(11) Place XTAL CUR switch to SUM
(c) TRIGGER SOURCE: EXT AC.
1, SUM 2, DIFF 1, and DIFF 2 positions and observe
(d) HORIZONTAL DISPLAY: X1.
XTAL CUR meter indication. Readjust LO ATTEN
(e) EXTERNAL VERNIER: CAL.
control for average indication of 0.6 ma for all four
(f) SWEEP TIME MICROSECONDS/
positions.
CM: 50.
(g) SWEEP TIME VERNIER: CAL.
NOTE
(h) Vertical Presentation: CHANNEL
A.
Do not replace covers on Radar Receiver-
(i) CHANNEL A AC-DC: AC.
Transmitter RT-818/TPN-18 until alignments and
(i)
CHANNEL
A
SENSITIVITY
adjustments are completed.
(VOLTS/CM): .02.
(k) CHANNEL A SENSITIVITY VER-
3-32. Sum Receiver Channel Alignment.
NIER: CALIBRATED.
(fig. 338)
a. Test Equipment Required.
(1) Multimeter ME-26A/U (vtvm).
(2) Oscilloscope AN/USM-140B (oscillo-
scope).
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