Keysight Technologies N5247B, Service Manual

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4-40 Keysight N5247B Service Guide
Troubleshooting
Measurement System Troubleshooting
4-
4. Refer to the NOTE notice on page 4-29 . Set the network analyzer for an
800 MHz CW frequency and observe the spectrum analyzer measurement.
or analyzers with DSP version 4.0, an 807.61 MHz signal should be
present. For analyzers with DSP version 5.0, an 807.44 MHz signal should
be present.
5. If the observed problem was frequency banded rather than broadband
related, set the analyzer frequency to the center of the problem band. The
spectrum analyzer should measure a signal above the network analyzer
setting. For analyzers with DSP version 4.0, the signal is 7.61 MHz above
the network analyzer setting. For analyzers with DSP version 5.0, the
signal is 7.44 MHz above the network analyzer setting.
6. If the LO signal is not present but the 50 MHz reference signal from
“Checking the A14 50 MHz Reference Outputs” is present, replace the A15
LO synthesizer board. Refer to “Removing and Replacing the A4–A17
Boards” on page 7-18 .
7. If the signal is present, reconnect cable W41, and then continue with
“Checking the A25 HMA26.5 Output” .
Checking the A25 HMA26.5 Output
1. Refer to the block diagram at the end of this chapter and to “4-Port
Configuration, Serial Number Prefixes <6021” on page 6-84 or in “4-Port
Configurations, Serial Number Prefix
≥
6021” on page 6-136 . Locate the
semirigid cable W52 (4-port models with a legacy HMA26.5) or W80
(2-port models and for all models with a new HMA26.5) at the A25
HMA26.5.
2. Disconnect W52 (4-port models with a legacy HMA26.5) or W80 (2-port
models and all models with a new HMA26.5) from the A25 HMA 26.5.
3. Connect the spectrum analyzer to the open connector on the A25 HMA
26.5.
4. Refer to the NOTE notice on page 4-29 . Set the network analyzer for an
800 MHz CW frequency and observe the spectrum analyzer measurement.
For analyzers with DSP version 4.0, an 807.61 MHz signal should be
present. For analyzers with DSP version 5.0, an 807.44 MHz signal should
be present.
5. If the observed problem was frequency banded rather than broadband
related, set the analyzer frequency to the center of the problem band. The
spectrum analyzer should measure a signal above the network analyzer
IMPORTANT! Some PNAs have installed a legacy HMA26.5 (5087-7765)
that is used with a discrete A26 splitter. Some PNAs have installed a new
HMA26.5 (N5240-60101) with an integrated splitter. To identify which
HMA26.5 is installed in your PNA, refer to Figure 4-12 on page 4-42 .