4-30 Service Guide N5242-90001
Troubleshooting PNA Series Microwave Network Analyzers
Measurement System Troubleshooting N5242A
• If the power level is low or high on all test ports, the problem is LO signal related.
Continue with “Checking the A10 50 MHz Reference Outputs”.
• If the power level is low or high on only one of the test ports, the problem is either
source group or in the signal separation group. Continue with “Checking the A10
50 MHz Reference Outputs” to check the source group.
Checking the A10 50 MHz Reference Outputs
1. Refer to the block diagram at the end of this chapter and to “Top Cables, All Cables—All
Options” on page 6-16. Locate flexible cables W65, W66, and W67, at the A10 frequency
reference board.
2. Disconnect cables W65, W66, and W67, one at a time, from the A10 board.
3. Connect the spectrum analyzer to the open connector on the A10 board.
4. The spectrum analyzer should measure a signal at 50 MHz.
5.
If any of the 50 MHz signals are not present, replace the A10 frequency reference board.
Refer to
“Removing and Replacing the A4–A13 Boards” on page 7-14
.
6. If the 50 MHz signals are present, reconnect the cables, and then:
• for LO related problems, continue testing at “Checking the A11 13.5 GHz LO
Synthesizer Output”.
• for source related problems, continue testing at “Checking the A4 and A13 Source
Synthesizer Outputs” on page 4-31.
Checking the A11 13.5 GHz LO Synthesizer Output
1. Refer to the block diagram at the end of this chapter and to “Top Cables, All Cables—All
Options” on page 6-16. Locate the flexible cable W41 at the A11 LO synthesizer board.
2. Disconnect W41 from J1207.
3. Connect the spectrum analyzer to J1207.
4. Set the network analyzer for a 500 MHz CW frequency and observe the spectrum
analyzer measurement.
• The spectrum analyzer should measure a signal at 507.61 MHz.
5. If the signal is not present and the 50 MHz reference signal is present from “Checking
the A10 50 MHz Reference Outputs,” replace the A11 LO synthesizer board. Refer to
“Removing and Replacing the A4–A13 Boards” on page 7-14.
6. If the signal is present, reconnect cable W41, and then continue with “Checking the A21
HMA26.5 Output”.
Checking the A21 HMA26.5 Output
1. Refer to the block diagram at the end of this chapter and to “Bottom RF Cables,
Standard 4-Port Configuration, Option 400” on page 6-42. Locate the flexible cable W42
at the A21 HMA26.5.
2. Disconnect W42 from the A21 HMA 26.5.
3. Connect the spectrum analyzer to the open connector on the A21 HMA 26.5.
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