A26 140 Mhz Wideband Digital If Troubleshooting - Keysight n9020a Service Manual

Analog/Digital IF Troubleshooting
≥ 85 MHz BW IF Section

A26 140 MHz Wideband Digital IF Troubleshooting

Verify the 300 MHz IF Input level
The A26 Digital IF has a single accessible input at A25J2. It is not advisable to
disconnect this cable and make measurements. Normally failure of this
assembly will occur during extensive alignments. Verify if there are alignment
error related to the WBDIF located in the
E:\AlignDataStore\AlignmentHistrory.txt files.
If errors are found related to WBDIF replace the A26 Wideband Digital IF
assembly. To troubleshoot this module set the instrument up as below:
1. Turn on the N9020A Signal Analyzer and wait for the instrument to
complete the boot up process.
2. Press System, Alignments, Auto Align, Off.
3. Press Mode, IQ Analyzer
4. Press Meas, Complex Spectrum
5. Press Input/Output, RF Calibrator, 50 MHz
6. Press Span, 10 MHz
7. Press Mode Setup, IF Path, 85, 125, or 140 MHz
8. Verify the 50 MHz signal is at −25 dBm on the analyzer display by pressing
Peak Search on the N9020A. The marker readout should be 50 MHz at
−25 dBm ±3 dB.
9. If this signal is not present, determine if the issue is only present with the
Wideband 85, 125, or 140 MHz path. Press Mode Setup, IF Path, 40 MHz.
If the signal is now present, there is a likely failure of the A26 Wideband
Digital IF or the A25 Wideband Analog IF
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