256 Keysight NFA Series Noise Figure Analyzers Service Guide
Analog/Digital IF Troubleshooting
25 MHz BW IF Section
Verifying the 22.5 MHz Output Power
1. Turn the instrument off.
2. Turn the instrument over so the bottom side of the analyzer is facing up.
3. Turn on the NFA and wait for the instrument to complete the boot up
process.
4. Press System, Alignments, Auto Align, Off.
5. Press Input/Output, RF calibrator, 50 MHz.
6. Verify the 50 MHz signal is at −25 dBm by pressing MODE/MEAS,
Spectrum Analyzer, OK, FREQ, 50 MHz, Span, 1MHz, Peak Search on the
analyzer. The marker readout should be 50 MHz at −25 dBm ± 3 dBm. If
this reference signal is measuring incorrectly, see Chapter 4, “RF Section
Troubleshooting (N8973B, 74B, 75B Analyzers)” in this service guide.
7. To continue verifying press FREQ, Zero Span. Verify the input attenuator
on the NFA is set to 10 dB. Look near the top of the display near the center
and verify that Atten: 10 dB is visible. If needed change the input
attenuator by pressing AMPTD, Attenuation, Mech Atten 10 dB on the
analyzer.
8. Refer to Figure 7-3, carefully disconnect the W13 cable at A3J15.
Figure 7-3 A3 Digital I.F. Cables
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