
Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-31. INTERNAL MODULATION OSCILLATOR DISTORTION TEST (Option 001) (Cont'd)
Figure 4-17. Internal Modulation Oscillator Distortion Test Setup.
EQUIPMENT:
Distortion Analyzer ................................................................................. HP 333A
600 Ohm Feedthrough ....................................................................... HP 11095A
PROCEDURE:
1. Connect equipment as shown in Figure 4-17 after setting Signal Generator's controls as follows:
AM ................................................................................................................. INT
AUDIO OUTPUT LEVEL .................................................................................3V
MODULATION FREQUENCY ........................................................... As specified
FM ...............................................................................................................OFF
2. Set the MODULATION FREQUENCY controls to various frequencies within the variable ranges shown below. At
each frequency tested, calibrate the distortion analyzer and measure the distortion. It should be as shown.
Frequency Range
Distortion
20 Hz to 2 kHz
<0.5%
2 kHz to 600 kHz
<1.0%
3. Set the MODULATION FREQUENCY controls to the 400 Hz and 1 kHz fixed frequencies. Distortion at both
frequencies should be below 0.25%.
400 Hz:______________0.25%
1 kHz:_______________0.25%
4-46
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