388 Keysight N9038A MXE Service Guide
Optional Assemblies
A25 Wideband Analog IF Assembly Troubleshooting
Overall Wideband Signal Path Verification
Before attributing a fault to the A25 Wideband Analog IF assembly its overall
ability to process a signal will need to be verified. However, due to its output
being that of the analog to digital converter (ADC) on the assembly the actual
output of the assembly itself cannot be verified, 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 14-2.
Figure 14-2 Overall Wideband Signal Path Verification
8. If the signal level measured is correct the overall basic functionality of the
A25 Wideband Analog IF assembly is working as it should. If not, proceed
with the rest of the verification listed in this section.
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