Recommended equipment, Recommended equipment -24 – Agilent Technologies E4438C User Manual
Page 72
Performance Tests
Timebase Aging Rate (Manual Test - Option UNJ, Option 506, or Option 1E5 Only)
3-24
Timebase Aging Rate
(Manual Test - Option UNJ, Option 506, 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 using the
“Agilent E4438C ESG Vector Signal Generator Timebase Aging Rate Performance Test
.
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
• Agilent 54610B digital oscilloscope
• Use a 10 MHz house standard. (For example, an Agilent 5071A primary frequency standard or equivalent
can be used.)