TM 11-6625-847-45
4-8. Test Set A2, If. Oscillator Modules A1A2, A1A3, and A1A4 Tests
The test of each oscillator module differs only in the operating frequency of the oscillator.
a. Test Equipment and Materials.
(1) Voltmeter, Electronic AN/URM-145.
(2) Electronic Counter, Digital Readout AN/URM-207.
(3) Fixed resistor: 51 ohms, 1/2 watt.
(4) Connector UG1460/U.
b. Test Connections and Conditions. Connect the equipment as shown in Figure 6-18. Figure 4-4 illustrates the if. oscillator module controls, jacks, and
test points.
c. Procedure.
Step
Control settings
No.
Test equipment
Equipment under test
Test procedure
Performance standard
1
AN/URM-145
SM442A/GRC
a. Set the PP-1451/G power
a. None.
Power switch: ON
POWER switch: OFF
switch and the test set
VOLTS switch: .01
SERV SEL switch: STBY
POWER switch to ON
PP-1451/G
PA/RT switch: PA
(test set supplied 27 volts
Power switch: OFF
KEY switch: OFF
dc).
NORMAL CHARGE
XMIT STATUS switch: OPR
b. Connect the AN/URM-145
b. Indication should be less
switch: NORMAL
REC-XMIT switch: REC
probe, in turn, to A1A2J1,
than 30 mv.
ALC VOLTAGE INFO control:
A1A3J1, and A1A4J1.
fully counterclockwise.
(For a more accurate indi-
ALC VOLTAGE TUNE con-
cation on the AN/URM-
trol: fully counterclockwise.
145, use a lower voltage
IF OSCILLATOR SELECT
range.) Change the IF
switch: 1+3 (change as re-
OSCILLATOR, SELECT
quired).
switch setting as required.
MC FREQ 10MC switch: 0
c. Turn the three IF OSCIL-
c. None.
MC FREQ 1MC switch: 0
LATOR output level con-
MC FREQ .1MC switch: 0
trols 1, 2, and 3 (A2R1,
500 VDC LOAD switch: LOW
A3R1, and A4R1) fully
2400 VDC LOAD switch: 1
clockwise.
IF OSCILLATORS 1, 2, and 3
d. Check to see that the AN/
d. The output voltage should
output level controls: fully
URM-145 VOLTS switch
be at least more than 300
counterclockwise.
is on the .01 range. Con-
mv.
nect the probe of the
AN/URM-145, in turn,
to A1A2J1, A1A3J1,
and A1A4J1, and record
each reading. Change the
IF OSCILLATOR select
switch setting as required.
e. Turn the AN/URM-145
e. None.
power switch off.
2
Same as above, except
Same as above, except set the
a. Turn the power switch on the
a. None.
that the AN/URM-
IF OSCILLATORS level
PP-1451/G and the POWER
145 is not used.
controls fully clockwise.
switch on the test set to
AN/USM-207
Note. If signal levels are
ON.
SENSITIVITY switch:
too low, an amplifier may be
b. Attach the Cable Assembly
b. The following should be
.1V
required to increase the signal
Radio Frequency from
displayed:
POWER switch:
to above.1 volt rms, to provide
FREQ A on the AN/USM-
(1) A1A431: 1.7500 mc,
TRACK
adequate input to the AN/USM-
207 to A1A2J1, A1A3J1,
100 cps.
DISPLAY control:
207.
and AMA4J1, in turn, and
(2) A1A3J1: 1.7515 mc,
Set for display time
record the frequency dis-
100 cps.
desired.
played at each test point.
(3) A1A2J1: 1.7525 mc,
100 cps.
and 6-3 to locate capacitor
vary more than +100 cps
C1 on each if. oscillator.
from the value recorded in
Rotate C1 on each if. oscil-
b above.
lator, respectively, through
its full travel, and record
the minimum and maximum
frequencies for each if.
d. Turn the POWER switch on
d. None.
the test set, the power
switch on the PP-1451/G,
and the POWER switch
on the AN/USM-207 to
OFF.
4-11
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