Service Guide N5230-90024 4-31
PNA Series Microwave Network Analyzers Troubleshooting
N5230C Measurement System Troubleshooting
A phase lock problem is due to either:
• faulty RF signal generation (caused by the A10, A9, A8, A17, A18, or A19 board)
• faulty LO signal generation (caused by the A10, A7 or A6 board)
RF Signal Troubleshooting
To isolate a broadband RF signal generation failure, check the test port output power:
1. Connect a power meter and power sensor to Port 1 of the analyzer.
2. On the analyzer, press
Preset, set the Center Frequency to 2 GHz, and the Frequency Span to 0 Hz. Note the
power reading displayed on the power meter.
NOTE In the unlocked state, the analyzer will “search” for the reference signal. The output power,
as indicated on the power meter, should be approximately 5dBm (20 GHz PNA), 10 dBm
(40 GHz PNA), or 15 dBm (50 GHz PNA).
3. Connect the power sensor to Port 2 and set trace to measure S
22
. Note the power reading displayed on
the power meter.
• If the power level is low on only one of the ports, the problem is in the signal separation group. Go to
“Checking the Signal Separation Group” on page 4-36.
Checking the A10 5 MHz Reference Output, All Bands
1. Refer to the block diagram at the end of this chapter and to “Top Cables, All Options” on page 6-14.
Locate flexible cable W27, at the A10 frequency reference board.
2. Disconnect W27 from A10J10.
3. Connect the spectrum analyzer to A10J10.
4. The spectrum analyzer should measure a signal at 5 MHz.
5. If the 5 MHz signal is not present, replace the A10 frequency reference board. Refer to “Removing and
Replacing the A5 through A10 Boards and the Plenum Bracket” on page 7-16.
6. If the 5 MHz signal is present, reconnect cable W27, and then continue testing at “Checking the A7
Fractional-N Synthesizer Output, Bands 1 and 2” on page 4-31.
Checking the A7 Fractional-N Synthesizer Output, Bands 1 and 2
1. Refer to the block diagram at the end of this chapter and to “Top Cables, All Options” on page 6-14.
Locate the flexible cable W2, at the A7 fractional-N synthesizer board.
2. Disconnect W2 from A7J101.
3. Connect the spectrum analyzer to A7J101.
4. Set the network analyzer for a 500 MHz CW frequency and observe the measurement.
• The spectrum analyzer should measure a signal at 500.2 MHz.
5. If the signal is not present and the 5 MHz reference signal is present from “Checking the A10 5 MHz
Reference Output, All Bands,” replace the A7 fractional-N synthesizer board. Refer to “Removing and
Replacing the A5 through A10 Boards and the Plenum Bracket” on page 7-16.
6. If the signal is present, reconnect cable W2, and then continue with “Checking the A7 Fractional-N
Synthesizer Output, Band 3” on page 4-32.
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