Atec Agilent-8563E - Manual (Page 73)

Performance Tests ESG Family Signal Generators
11. Timebase Aging Rate (ESG-AP, ESG-DP or Option 1E5 only)
4-24 Calibration Guide
11. Timebase Aging Rate
(ESG-AP, ESG-DP or Option 1E5 only)
This manual test verifies the accuracy of the signal generator’s internal timebase. The
time required for a 360
°
phase change is measured both before and after a specified
waiting period. The aging rate is inversely proportional to the absolute value of the
difference in the measured times. The results of this test can be recorded on the test record
provided on
page 4-48 .
The overall accuracy of the internal timebase is a function of:
TBC
±
AR
±
TE
±
LE where:
TBC = timebase calibration
AR = aging rate
TE = temperature effects
LE = line effects
After the timebase is adjusted, the timebase frequency should stay within the aging rate
for the following situations:
• The timebase oven does not cool down.
• The instrument keeps the same orientation, with respect to the earth’s magnetic field.
• The instrument stays at the same altitude.
• The instrument does not receive any mechanical shock.
If the timebase oven cools (the instrument power switch is set to off), you may have to
readjust the timebase frequency after a new warm-up cycle. Typically, however, the
timebase frequency returns to within
±
1 Hz of the original frequency.
NOTE The internal timebase can be tested after the AC power is reconnected for 10
minutes. For best accuracy, retest after the instrument has been on for 24
hours.
Frequency changes due to either a change in orientation, with respect to the earth’s
magnetic field, or to a change in altitude usually go away when the instrument is returned
to its original position. A frequency change due to mechanical shock usually appears as a
fixed frequency error.
Recommended Equipment
• HP/Agilent 54610B Digital Oscilloscope
• HP/Agilent 5071A Primary Frequency Standard