Keysight N9038A MXE Service Guide 335
Analog & Digital IF
A2 Analog I.F. Troubleshooting
A2 Analog IF 25 MHz Filter Path (Option B25 Only)
This filter is only available with the optional 25 MHz analysis bandwidth, and
only when using certain instrument application software. It is not available in
either the Spectrum Analyzer or EMI Receiver modes. For this reason this will
be verified with the IQ Analyzer mode.
1. Remove the instrument dress cover (MP24) and top brace (MP10). Refer to
Chapter 18, “Assembly Replacement Procedures” for instructions on
removing these covers.
2. Turn the instrument on and allow it to complete its boot up process.
3. Remove W17 from the A3 Digital IF assembly J19 as shown in Figure 10-2.
4. Connect the end of W17 to a spectrum analyzer tuned to 22.5 MHz.
5. Switch the instrument into the IQ Analyzer mode by pressing Mode, IQ
Analyzer.
6. Turn the instrument self-alignment routine off by pressing System,
Alignments, Auto Align, Off.
7. Tune the instrument to a center frequency 50 MHz pressing FREQ,
50 MHz.
8. Connect a sine wave signal generator to the instrument input.
9. Tune the signal generator to 50 MHz with an amplitude of -20 dBm.
10.Verify that the instrument resolution bandwidth is set to 25 MHz by
pressing Meas Setup, More, Advanced, Digital IF BW 25 MHz.
11.Set the spectrum analyzer span to 40 MHz
12.Set the spectrum analyzer such that trace 1 is in Clear Write and trace 2 is
in Maxhold.
13.Vary the frequency of the signal generator above and below 50 MHz until
the resolution bandwidth filter shape has been drawn out on the
spectrum analyzer screen as shown in Figure 10-10.
Since the A2 Analog IF assembly is not in an easily accessible area of the instrument its
22.5 MHz output will be measured on the other end of the cable coming from this assembly,
which is connected to J19 of the A3 Digital IF assembly.
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