
Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-45. PHASE LOCK RESTABILIZATION TIME TEST (Cont'd)
NOTE
For these tests, ambient room temperature and line voltage should not change.
EQUIPMENT:
Frequency Counter................................................................HP 5327C OPT 003
Digital to Analog Converter .................................................... HP 581A OPT 002
Recorder (for D/A Converter) ................................................................... HP 680
PROCEDURE:
1. Connect equipment as shown in Figure 4-1 after setting Signal Generator's control as follows:
COUNTER MODE: EXPAND .......................................................................... Off
LOCK .............................................................................. Off
Source ........................................................................... INT
AM ................................................................................................................OFF
FM ................................................................................................................OFF
RANGE ............................................................................................32 - 64 MHz
FREQUENCY TUNE ...............................................................................50 MHz
RF ON/OFF ....................................................................................................ON
2. Warm up equipment for two hours. Then set frequency counter to read frequency directly (i.e., not divided down).
Use a is gate time so that the last two digits span from 00 to 99 Hz.
3. Calibrate the recorder for a zero to full-scale reading that corresponds to a 00 to 99 Hz reading of the frequency
counter's last two digits (i.e., 100 Hz full scale).
4. Set COUNTER MODE LOCK to ON, wait one minute, then record generator's output frequency for five minutes; the
frequency should not vary more than 7 Hz (<0.1 ppm +1 digit counter ambiguity).
--------7 Hz
5. Set COUNTER MODE LOCK to Off; tune FREQUENCY TUNE control fully ccw and back again to approximately 50
MHz. Repeat step 4; frequency should not vary more than 7 Hz.
--------7 Hz
6. Set COUNTER MODE LOCK to Off; set RANGE switch to 64 128 MHz and back again to 32 64 MHz. Repeat step 4;
frequency should not vary more than 7 Hz.
--------7 Hz
7. Set COUNTER MODE LOCK to Off; set RF ON/OFF switch to OFF. Wait one minute and set RF ON/OFF switch to
ON. Repeat step 4; frequency should not vary more than 7 Hz.
--------7 Hz
4-76
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