168 N9030B PXA Signal Analyzer Service Guide
RF Section Troubleshooting (RF/Microwave Analyzers)
Troubleshooting
To perform the YTF alignment, reconnect W15 cable, and press System,
Alignments, More, Ad vanced, Characterize Preselector. The routine may take
several minutes to align the YTF. Display the 4.8 GHz calibrator signal on
screen as explained in the quick check section. If the signal level is still
incorrect, suspect all assemblies, cables, switches and the A16 Reference
calibrator signal between the W15 cable and the input to the A9 Attenuator.
If Option MPB is not present, remove A10 Input Attenuator B output cable and
measure the output power. Expected signal is 4.8 GHz −38 dBm. See Figure
4-8 for location of attenuator. If the attenuator output signal is correct suspect
the A11 Low Band Switch, and if Option MPB or LNP is installed, suspect
switches 1,2,3. Also suspect the switching signals from the A15 Front End
controller. The control signals are explained in the Front End Control
Troubleshooting section.
Figure 4-8 RF Section
A9 Input Attenuator A and A10 Input Attenuator B Verification
Calibrator Switch Test
On the A16 Reference assembly, disconnect semi rigid cable W3 from A16J701
and measure A16J701 with a spectrum analyzer. Expected signal is 4.8 GHz at
−28 dBm ± 0.5 dB. If signal level is incorrect, suspect A16 Reference Assembly.
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