
Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-21. RESIDUAL AM TEST (Cont'd)
Meter Function ..................................................................................................................................... LEVEL
COUNTER MODE:
EXPAND ................................................................................... Off
LOCK........................................................................................ Off
Source ..................................................................................... INT
AM............................................................................................................................................................. INT
MODULATION ................................................................................................................................... Full ccw
MODULATION FREQUENCY............................................................................................................. 1000 Hz
FM............................................................................................................................................................ OFF
RANGE .................................................................................................................................... 256 - 512 MHz
FREQUENCY TUNE ......................................................................................................................... 500 MHz
OUTPUT LEVEL...................................................................................................... +13 dBm (Vernier full cw)
RF ON/OFF................................................................................................................................................ON
2.
Set Meter Function to AM and slowly turn Signal Generator's MODULATION control clockwise until its panel meter
indicates 10% AM. Note voltmeter reading in dB.
3.
Set generator's AM switch to OFF. The residual AM should read >58 dB below the reference noted in step 2 (i.e.,
>78 dB down). (The 10% AM, after detection, is 20 dB below the carrier level. Residual AM is then 20 dB -78 dB
= -58 dB.)
58 dB ___________________________
4.
Replace the 15 kHz LPF with the 3 kHz LPF. Add the capacitor between amplifier and filter and repeat steps 1
through 3. The residual AM should read >65 dB below the reference noted in step 2 (i.e., > 85 dB down).
65 dB ___________________________
4-22. RESIDUAL FM TEST
SPECIFICATION:
Residual FM:
(Averaged rms)
CW and up to 1/8 maximum
Up to maximum allowable
allowable peak deviation
peak deviation
Post-detection
300 Hz
20 Hz
300 Hz
20 Hz
Noise
to
to
to
to
Bandwidth
3 kHz
15 kHz
3 kHz
15 kHz
230 to 550
<5 Hz
<15 Hz
<15 Hz
<30 Hz
MHz
4-21
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