Troubleshooting A High Band Problem - Keysight N8973B Service Manual

RF Section Troubleshooting (N8976B)
Troubleshooting

Troubleshooting a High Band Problem

Refer to the RF Highband Path #1 Block Diagram (N8976B) in
follow the instructions in the settings box. To enable the internal 4.8 GHz,
−28 dBm calibrator signal press MODE/MEAS, Spectrum Analyzer, OK,
Input/Output, RF Calibrator, 4.8 GHz.
A13 Front End Input Verification
Disconnect W7 from A13J9 See
the other end of W7 if possible to avoid damaging the cable. Attach a right
angle SMA adapter to W7 and measure the input to the A13 Front End with a
spectrum analyzer.
Figure 5-10 A13J9 Location
Expected signal is 4.8 GHz at −51 dBm ± 4 dB. The tolerance is large because
the A12 YTF (microwave preselector) loss varies between devices, and the YTF
may not be perfectly aligned, or the frequency response adjustment may be
required.
To perform the YTF alignment, reconnect W7 cable, and press System,
Alignments, Ad vanced, Characterize Preselector. The routine may take
several minutes to align the YTF. Display the 4.8 GHz calibrator signal on
Keysight NFA Series Noise Figure Analyzers Service Guide
Figure 5-10 for location of connector. Loosen
Chapter 12 and
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