TB 9-4931-488-24
Table 20. AM Accuracy.
Measuring receiver % AM
Test instrument meter
indications (%)
indications (%)
Min
Max
90
83.6
96.5
70
64.7
75.4
50
45.8
54.3
30
26.9
33.2
20
17.4
22.6
10
7.95
12.1
(8)
Adjust AM control for a 50% AM indication on measuring receiver.
(9) Press LEVEL VOLTS pushbutton and adjust OUTPUT LEVEL vernier
control(s) for a +3 dB indication on TI meter. The distortion, as indicated on the measuring
receiver, should be within limits listed in table 21. Press AM X10%.
(10) Repeat technique of (8) and (9) above for TI meter dB indications and measuring
receiver % AM indications listed in table 21. The measuring receiver modulation distortion
indications should be as specified.
Table 21. AM Distortion.
Test instrument meter
Measuring receiver % AM
Measuring receiver
Indications (dB)
Indications (%)
distortion indications (< %)
+3
50
1
+3
90
3
-7
90
3
-7
50
1
-7 1
30
10
-7 1
90
20
1
Perform for option 002 only. Set RANGE MHz switch to 1024-512 and adjust FREQUENCY TUNE control for a
FREQUENCY MHz display indication of 1024 MHz.
(11)Set AM and RF OFF/ON switches to OFF.
b. Adjustments
(1) Position controls as listed in (a) through (f) below.
(a) AM switch to AC.
(b) AM control fully cw.
(c) OUTPUT LEVEL vernier control(s) fully cw.
(d) RANGE MHz switch to 64-32.
(e) FREQUENCY TUNE control for FREQUENCY MHz display indication of 50 MHz.
(f) RF OFF/ON switch to ON.
(2) Set pulse generator for a 1 kHz, 0.7072 V, 600 Ω output signal.
(3) Set measuring receiver to measure peak AM with 50 Hz high-pass and 15 kHz
low-pass filters. Adjust A26A2R19 (%AM, fig. 2) for a 50.0 0.1% measuring receiver
indication.
(4) Set AM and RF OFF/ON switches to OFF and repeat paragraph 15 a above.
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