Agilent Technologies N5230A Service Manual page 107

PNA Series Microwave Network Analyzers
N5230A
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
to . Note the power reading displayed on the power meter.
0 Hz
In the unlocked state, the analyzer will "search" for the reference signal. The
NOTE
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
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"
• 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
• If the output power is high on both test ports the problem is LO signal related Continue
with "LO Signal Troubleshooting"
LO Signal Troubleshooting
To isolate a broadband LO signal generation failure, refer to the data obtained from the
"Serial Bus Test" on page
• 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
• 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
• 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
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.
Service Guide N5230-90014
, set the
Preset Center Frequency
below.
below.
4-31:
Measurement System Troubleshooting
to , and the
2 GHz
. Note the power
22
4-42.
page
page 4-40.
"Top Cables, All Options" on
Troubleshooting
Frequency Span
4-37.
4-37