artisan 8640B - Page 124

Model 8640B TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-37. PULSE ON/OFF RATIO TEST
SPECIFICATION:
Pulse ON/OFF ratio at maximum vernier: >40 dB.
DESCRIPTION:
The on/off ratio of the pulse modulation circuits is measured with a spectrum analyzer.
EQUIPMENT:
Spectrum Analyzer...........................................................HP 141T/8552B/8554B
PROCEDURE:
1. Connect generator's RF OUTPUT to analyzer's input after setting Signal Generator's controls as follows:
Meter Function..........................................................................................LEVEL
COUNTER MODE: EXPAND ..........................................................................Off
LOCK ..............................................................................Off
Source ........................................................................... INT
AM................................................................................................................OFF
FM ................................................................................................................OFF
RANGE ........................................................................................256 - 512 MHz
FREQUENCY TUNE .............................................................................256 MHz
OUTPUT LEVEL.............................................................-7 dBm (Vernier full cw)
RF ON/OFF ....................................................................................................ON
2. Set spectrum analyzer's input attenuation to 20 dB. Adjust center frequency controls to center the 256 MHz signal on
the display. Adjust scale reference level controls to set the signal to the top (O dB) graticule line with the scale
controls set to display 10 dB per division.
3. Set generator's AM switch to PULSE. The signal on the analyzer's display should decrease more than 40 dB.
40 dB
4. Repeat steps 1 through 3 with the RANGE switch set to each of its other positions. At each position, the signal on the
analyzer's display should decrease more than 40 dB.
40 dB
4-60
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