
Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-36. PULSE MODULATION TEST (Cont'd)
4. Set test Signal Generator's AM switch to OFF and adjust oscilloscope's vertical controls for 6 divisions of deflection
on the display (peak to peak).
5. Set test Signal Generator's AM switch to PULSE. Pulse amplitude (peak to peak) on oscilloscope's display should be
5.4 to 6.7 divisions.
Level Accuracy 5.4 6.7 div
6. Repeat steps 1 through 5 for the frequency ranges shown below. The rise and fall times and level accuracy should be
as specified.
Signal Generator
Pulse Generator
Frequency
Pulse
Pulse
Rise Time
Fall Time
Level Accuracy
RANGE
Rate
Width
1 - 2 MHz
100 Hz
µs
<4,us
<4 µs
5.4 _________ 6.7 div
2 - 4 MHz
200 Hz
5 us
<2 us
<2 µs
5.4 _________ 6.7 div
4 - 8 MHz
200 Hz
5 µs
<2 /is
<2 µs
5.4 _________ 6.7 div
8 - 16 MHz
500 Hz
2 µs
<1 us
<1 µs
5.4 _________ 6.7 div
16 - 32 MHz
500 Hz
2 µs
<1 µs
<1 µs
5.4 _________ 6.7 div
7. Connect test generator to mixer and mixer to oscilloscope (across 50 ohm load).
8. Repeat steps 2 through 5 for the frequency ranges shown below. At each frequency range, set the pulse generator as
specified, and set the reference signal generator for an output frequency 10 MHz below the output frequency of the
test generator. The reference generator's output should be at +7 dBm with no modulation.
Signal Generator
Pulse Generator
Frequency
Pulse
Pulse
Rise Time
Fall Time
Level Accuracy
RANG E
Rate
Width
32 - 64 MHz
500 Hz
2 µs
<1 µs
<1 µs
5.4 __________6.7 div
64 - 128 MHz
500 Hz
2 µs
<1 µs
<1 µs
5.4 __________6.7 div
128 - 256 MHz
500 Hz
2 µs
<1 µs
<1 µs
5.4 __________6.7 div
256 - 512 MHz
500 Hz
2 µs
<1 µs
<1 µs
5.4 __________6.7 div
9. Increase the test Signal Generator's RF OUTPUT LEVEL one step cw and reduce the vernier to give -17 dBm.
Repeat steps 3 to 8.
4-59
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