
Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-41. INCIDENTAL AM TEST (Cont'd)
PROCEDURE:
1. Connect equipment as shown in Figure 4-27 (with network, adapter, tee, and detector connected as shown) after
setting Signal Generator's controls as follows:
Meter Function ................................................................................................AM
COUNTER MODE: EXPAND .......................................................................... Off
LOCK .............................................................................. Off
Source ........................................................................... INT
AM ................................................................................................................ INT
MODULATION ....................................................................................... Full ccw
MODULATION FREQUENCY .................................................................... 1 kHz
FM ................................................................................................................OFF
PEAK DEVIATION ................................................................................ 2.56 MHz
PEAK DEVIATION Vernier ....................................................................... Full cw
RANGE ........................................................................................ .256 - 512 MHz
FREQUENCY TUNE ............................................................................. 256 MHz
OUTPUT LEVEL .......................................................... +13 dBm (Vernier full cw)
RF ON/OFF ....................................................................................................ON
2. Set MODULATION for 10% AM as read on panel meter.
3. Adjust oscilloscope's vertical gain controls so that the 1 kHz signal has 8 divisions of peak-to-peak deflection (i.e.,
1.25% AM per division).
4. Set generator's AM switch to OFF and FM switch to INT. Set Meter Function to FM and set PEAK DEVIATION
vernier for 2.56 MHz. Increase oscilloscope sensitivity by 10. Using generator's FREQUENCY TUNE control, tune
across the band and record the maximum incidental AM read on the oscilloscope. It should be less than 1% (8
divisions peak-to-peak on the display).
Maximum Deivation: 1%
5. Set PEAK DEVIATION switch to 320 kHz. Again, using the generator's FREQUENCY TUNE control, tune across the
band. Incidental AM should be less than 0.5% (4 divisions peak-to-peak on the display).
1/8 Maximum Deviation: 0.5%
NOTE
Incidental AM is usually worse case on the 256 512 MHz band. If desired, it can be checked on
any other band using this test except that on the 0.5 to 16 MHz bands the capacitor across the
resistor at the detector's output must be changed to 0.033, F (HP 0160-0163); on the 16 to 512
MHz bands, the 0.001/ F capacitor (shown in the test setup) must be used.
4-69
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