TM 11-6625-1702-35
F'igure 4-4. TUNE INDICATOR function test, waveform.
4-7. TUNE INDICATOR Function Test
a. Test Equipment and Materials.
(1) Power supply, 28-volt dc.
(2) Oscilloscope AN/USM-140A.
(3) Antenna Coupler, 437S-1/1A.
c. Procedure.
Control
settings
Step
Performance
standard
No.
Test procedures
Test equipment
Equipment under test
a. Test set meter indicates
a. Adjust power supply to
1 a. Turn on power
a. Set METER FUNC-
27.5 1.3 volts dc.
supply and al-
obtain 27.5-volt indi-
TION switch to
low time for
28 VDC.
cation on power sup-
ply meter.
warmup.
b. None.
b. Turn on oscillo-
b. Rotate MV ADJUST
b. Connect MV OUTPUT
scope and al-
terminals to FL1 and
fully counterclockwise.
FL5 of antenna coup-
low time for
ler. Connect FL4 to
warmup.
ground (fig. 4-3).
NOTE
If antenna coupler 4375-1 is used, perform step 1c and skip 1d; otherwise, skip step 1c.
c. Should read open
c. Measure resistance
c. None.. . . . . . . . . . . . . . c. Turn off power. S2 to
circuit.
from J4-A to Gnd.
"OFF."
Should read <1 ohm.
S2 to "Decrease Freq." . . . . . . . . . Measure resistance
from P2-A to Gnd and
J4-A to Gnd.
Should read open
S2 to "OFF." . . . . . . . . . . . . . . . . . Measure resistance
circuit.
from J4-B to Gnd.
Should read <1 ohm.
S2 to "Increase Freq." . . . . . . . . . Measure resistance from
P2-B to Gnd and from
J4-B to Gnd.
Turn on power . . . . . . . . . . . . . . .. None . . . . . . . . . . . . . . . . . . . . . . .. None
d. Monitor motor pulsing
d. None . . . . . . . . . . . . . . d. Momentarily set MAN-
UAL TUNE switch
similar to that in figure
signal on oscilloscope.
4-4.
S2 to either IN-
CREASE FRE-
QUENCY or DE-
CREASE FRE-
QUENCY.
e. Repetition period of
e. None . . . . . . . . . . . . . . . e. None . . . . . . . . . . . . . . . . . . . . . . e. Increase repetition rate
motor pulsing signal is
of motor pulsing sig-
155ms.
nal by rotating MV
ADJUST until TUNE
INDICATOR illumi-
nates brightly.
4-5
Change 2
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