
Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-39. FM DISTORTION TEST (Cont'd)
DESCRIPTION:
The Signal Generator is modulated with a 1 kHz signal. The generator's RF output is then demodulated with an FM
discriminator and the distortion on the discriminator output is measured with a spectrum analyzer.
Figure 4-25. FM Distortion Test Setup
EQUIPMENT:
FM Discriminator ................................................................................. HP 5210A
Filter Kit (For Discriminator) ............................................................... HP 10531A
Audio Spectrum Analyzer ................................................ HP 141T/8552B/8556A
PROCEDURE:
1. Connect equipment as shown in Figure 4-25 after setting Signal Generator's controls as follows:
Meter Function . ............................................................................................FM
COUNTER MODE: EXPAND .......................................................................... Off
LOCK ................................................................................................. Off
Source ............................................................................ INT
AM ................................................................................OFF
MODULATION FREQUENCY ......................................................... 1 kHz (Fixed)
FM
.......................................................................................................... INT
PEAK DEVIATION ................................................................................... .80 kHz
PEAK DEVIATION Vernier ....................................................................... Full cw
RANGE ................................................................................................8 -16 MHz
FREQUENCY TUNE ..................................................................................8 MHz
OUTPUT LEVEL .......................................................... +13 dBm (Vernier full cw)
RF ON/OFF ....................................................................................................ON
4-63
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