Anritsu MG3702xA Series, Maintenance Manual

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Chapter 3 — Performance Verification 3-6 Internal Time Base Aging Rate Test (Optional)
MG3702xA MM PN: 10370-10372 Rev. B 3-5
3-6 Internal Time Base Aging Rate Test (Optional)
For the following test, refer to the test record table in Appendix A , “Section 3-6 Internal Time Base Aging Rate
Test (Optional)” .
The following test can be used to verify that the MG3702xA 100 MHz time base is within its aging
specification. The instrument derives its frequency accuracy from an internal oven controlled 100 MHz crystal
oscillator standard. An inherent characteristic of crystal oscillators is the effect of crystal aging within the first
few days to weeks of operation. Typically, the frequency of the crystal oscillator increases slightly at first, then
settles to a relatively constant value for the rest of its life.
For the greatest absolute frequency accuracy, allow the MG3702xA to warm up until its RF output frequency
has stabilized (usually 7 to 30 days). Once stabilized, the change in reference oscillator frequency should
remain within the aging rate if (1) the time base oven is not allowed to cool, (2) the instrument orientation with
respect to the earth’s magnetic field is maintained, (3) the instrument does not sustain any mechanical shock,
and (4) ambient temperature is held constant. This test should be performed upon receipt of the instrument
and again after several days or weeks to fully qualify the aging rate.
Test Setup
Connect the MG3702xA rear panel 10 MHz REF OUT to the Symmetricom (Datum) model 9390-9600
frequency standard rear panel BNC connector labeled J10 using a BNC cable with 50 ohm termination and
BNC tee. The frequency standard must be actively tracking at least three satellites, and the oscillator should
be stabilized/locked. To confirm, the front panel TRACKING and LOCKED LEDs should be illuminated.
Procedure
1. Cycle the menu screen to the sixth screen (External Frequency Measurement) as shown below.
2. On the keypad, press
1
followed by the number 10000000. This will input the test frequency of 10 MHz.
Note
Do not confuse crystal aging with other short term frequency instabilities, for example, noise and
temperature. The internal time base of the instrument may not achieve its specified aging rate before
the specified warm-up time of 7 to 30 days has elapsed; therefore, this performance test is optional.
Note
Before performing this procedure ensure that all test equipment is calibrated. Refer to the
manufacturer’s test equipment manual.
Figure 3-1. Equipment Setup for Internal Time Base Aging Rate Tests
MG3702xA (DUT)
J10 BNC Port
10 MHz REF IN
Symmetricom (Datum)
Frequency Reference
Model 9390-9600
MG37022A
Signal
Generator
Standby Operate
Row 1 EXT Freq: +0000E-14 / +0000E+00 SEC *
Row 2 <1>Enter Freq <2>ENABLE <3>DISABLE