Keysight N9038A MXE Service Guide 397
Optional Assemblies
A26 Wideband Digital IF Assembly Troubleshooting
Internal Alignment Failures
Failure of this assembly will normally occur when the instrument internal
alignments are run, either automatically in the background or manually. To
verify if there are alignment errors related to the A26 Wideband Digital IF
assembly look in the file named:
E:\AlignDataStore\AlignmentHistrory.txt
If there are failures for items with names or descriptions such as WBDIF, WBIF,
or WideBandIF the most likely cause will be either a defective A25 Wideband
Analog IF or A26 Wideband Digital IF assembly.
Overall Wideband Signal Path Verification
Before attributing a fault to the A26 Wideband Digital IF assembly its overall
ability to process a signal will need to be verified. However, due to its input and
output being a digital bus it would be very difficult to isolate and verify the
functionality of the assembly itself, only the A25 Wideband Analog IF and A26
Wideband Digital IF assemblies working together can be verified. The following
procedure will verify this.
1. Turn the instrument on and allow it to complete its boot up process and
initial alignments
2. Make sure that the RF preselector is turned off by pressing Mode, EMI
Receiver, Input / Output, RF Input, RF Preselector Off
3. Turn on the internal 50 MHz calibrator signal by pressing Input / Output,
RF Calibrator, 50 MHz
4. Switch the instrument to IQ Analyzer mode by pressing Mode, IQ Analyzer
(Basic)
5. Tune the instrument to 50 MHz by pressing FREQ Channel, 50 MHz
6. Switch the instrument IF signal path to go through the A25 Wideband
Analog IF assembly by pressing Mode Setup, IF Path, 85 MHz
7. Measure the signal level by pressing Peak Search. The level of the 50 MHz
calibrator should be -25.0 dBm ±0.3 dB, as shown in Figure 14-7.
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