Keysight N5224A/25A Service Guide 4-39TroubleshootingMeasurement System TroubleshootingChecking the A7, A8, A12, and A13 50 GHz Doubler Outputs1. Refer to the block diagram at the end of this chapter and to “TopAssemblies and Cables, All Options” on page 6-16. Locate cable W11 onthe A7 doubler board, cable W17 on the A8 doubler board, cable W13 onthe A12 doubler board, and cable W15 on the A13 doubler board. (A12 andA13 are only available in 4-port models and 2-port models with Option224.)2. Disconnect cable W11 or W17 or W13 or W15, dependent on whichdoubler board is to be checked.3. Connect the spectrum analyzer to the open connector on the doublerboard to be checked.4. Set the network analyzer for an 800 MHz CW frequency and observe thespectrum analyzer measurement. An 800 MHz signal should be present.5. Refer to the Note on page 4-28. If the observed problem was frequencybanded rather than broadband related, set the analyzer frequency to thecenter of the problem band. The spectrum analyzer should measure asignal above the network analyzer setting. For analyzers with DSP version4.0, the signal is 7.61 MHz above the network analyzer setting. Foranalyzers with DSP version 5.0, the signal is 7.44 MHz above the networkanalyzer setting.6. If the signal is not present but the signals from “Checking the A4 and A17Source Synthesizer Outputs” are present, replace the appropriate doublerboard. Refer to “Removing and Replacing the A4–A17 Boards” onpage 7-14.7. If the signal is present, reconnect all cables, and then continue with“Checking the Signal Separation Group” on page 4-39.Checking the Signal Separation GroupBefore checking the signal separation group assemblies, you must open theanalyzer.1. Turn off the analyzer power.2. Unplug the power to the analyzer and disconnect all front and rear panelconnections except installed jumpers.Use an antistatic work surface and wrist strap to reduce the chance ofelectrostatic discharge for all of the procedures in this chapter.
