Keysight NFA Series Noise Figure Analyzers Service Guide     173
RF Section Troubleshooting (N8973B, 74B, 75B Analyzers)
Troubleshooting
Troubleshooting a High Band Problem
1. Reference Assembly Verification
Refer to Figure 4-22. Remove cable W19 from A9 Input Attenuator A (1). 
Measure the 4.8 GHz calibrator signal on the cable end with a functioning 
Spectrum Analyzer. 
Figure 4-22  W19 Location