Keysight N9038A MXE Service Guide 181
RF Preselector Section
RF Preselector Section Troubleshooting
Input Signal Routing and Pre-Filtering
There are two different pre-filter paths through the input routing of the A21 RF
Preselector Input assembly to be verified, as seen in Figure 5-8.
Figure 5-8 A21 RF Preselector Input Assembly Input Pre-Filters
Verifying Input Signal Routing and Pre-Filter Shape
1. Remove the instrument dress cover (MP24) and the top brace (MP10).
Refer to Chapter 18, “Assembly Replacement Procedures” for instructions
on removing these covers.
2. Referring to Figure 5-4, remove W31, W32, and W34 from the A21 RF
Preselector Input assembly.
3. Turn the instrument on and allow it to complete its boot up process,
ignoring any error messages.
4. Turn the instrument self-alignment routine off by pressing System,
Alignments, Auto Align, Off.
Input Signal Routing Verification - Conducted Band
5. Connect a signal generator to the A21 RF Preselector Input assembly RF
Input (J100), as shown in Figure 5-4.
6. Tune the signal generator to 10 MHz with an amplitude of −20 dBm.
7. Connect a spectrum analyzer to the A21 RF Preselector Input assembly
Conducted Band Pre-Filtered Output (J103), as shown in Figure 5-4.
8. Tune the spectrum analyzer to a frequency of 50.5 MHz with a span of
100 MHz.
9. Tune the instrument to a frequency of 10 MHz with a span of 0 Hz by
pressing FREQ, 10 MHz, and SPAN, Zero Span.
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