
Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-21. RESIDUAL AM TEST
SPECIFICATION:
Residual AM:
(Averaged rms)
Post-detection Noise Bandwidth
300 Hz to 3 kHz
20 Hz to 15 kHz
>85 dB down
>78 dB down
DESCRIPTION:
An rms voltmeter is calibrated with a measured amount of amplitude modulation from the Signal Generator. Then the
AM is removed and the generator's residual AM is read directly from the voltmeter.
Figure 4-8. Residual AM Test Setup
EQUIPMENT:
RMS Voltmeter .........................................................................................................HP 3400A
Detector....................................................................................................................HP 8471A
3 kHz Low-Pass Filter (LPF) ........................................................................ CIR-Q-TEL 5 Pole
15 kHz Low-Pass Filter (LPF) ...................................................................... CIR-Q-TEL 7 Pole
40 dB Amplifier ...........................................................................................................HP 465A
Capacitor 5
µ
F .................................................................................................. HP 0180-2211
50 Ohm Load..........................................................................................................HP 11593A
PROCEDURE:
1.
Connect equipment as shown in Figure 4-8 (with the generator connected to the rms voltmeter through the
detector, amplifier, 15 kHz LPF, and across the 50 ohm load). Set Signal Generator's controls as follows:
4-20
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