Service Guide N5230-90014 4-37
PNA Series Microwave Network Analyzers Troubleshooting
N5230A Measurement System Troubleshooting
A phase lock problem is due to either:
• faulty RF signal generation (caused by the A10, A9, A8, 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
0 dBm.
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 both ports, the problem is LO signal related. Continue with
“LO Signal Troubleshooting” below.
• 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 4-42.
• If the output power is high on both test ports the problem is LO signal related Continue
with “LO Signal Troubleshooting” below.
LO Signal Troubleshooting
To isolate a broadband LO signal generation failure, refer to the data obtained from the
“Serial Bus Test” on page 4-31:
• If the data obtained for the A10 frequency reference board is out of tolerance, confirm
the failure with the following checks for the A10 board starting on page 4-37.
• If the data obtained for the A10 frequency reference board is correct but the data for the
A7 fractional-N synthesizer board is out of tolerance, confirm the failure with the
following checks for the A7 board on starting on page 4-40.
• If the data obtained for the A9 fractional-N synthesizer board is correct—and the RF
has been checked—but there is still a phase lock problem, confirm the failure with the
following checks.
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 6-12. Locate flexible cable W28, at the A10 frequency reference board.
2. Disconnect W28 from A10J10.
3. Connect the spectrum analyzer to A10J10.
4. The spectrum analyzer should measure a signal at 5 MHz.
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