Agilent Technologies N5241A, Service Manual

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Service Guide N5242-90001 4-35
PNA Series Microwave Network Analyzers Troubleshooting
N5241A/42A Measurement System Troubleshooting
• A25, A26, A27, or A28 bridge
• A34, A35, A36, or A37 source step attenuator
• A38, A39, A40, or A41 bias tee
• A29, A30, A31, or A32 test port coupler
Equipment Used for These Tests
To determine which assembly is defective, check the signal at each available measurement
point in the signal path from the output of the source board to the output port.
Set the network analyzer for an S
11,
S
22,
S
33,
or S
44,
measurement for Port 1, 2, 3, or 4
respectively, with a CW frequency of 800 MHz.
Perform the following checks in the order presented.
Checking the A25, A26, A27, and A28 Bridges
1. Locate the appropriate semirigid cable at the output of the bridge to be checked:
• Options 200 and 400
— Port 1; W11 of A25
— Port 2; W23 of A28
— Port 3; W15 of A26
— Port 4; W19 or A27
• Options 219, 224, 419, and 423
— Port 1; W71 of A25
— Port 2; W83 of A28
— Port 3; W75 of A26
— Port 4; W79 of A27
2. Using a 5/16-inch torque wrench, disconnect the semirigid cable at the bridge.
3. Connect the spectrum analyzer to the open bridge connector. Set the spectrum analyzer
to measure a signal at 800 MHz.
4. If the 800 MHz signal is not present and the analyzer has mechanical switches,
continue testing at “Checking the A46, A47, A48, and A49 Mechanical Switches” on
page 4-36 .
5. If the 800 MHz signal is not present and the analyzer does not have mechanical
switches, replace the bridge. Refer to “Removing and Replacing the A25–A28 Bridges
and Bridge Mounting Brackets” on page 7-36 .
Equipment Type
Model or
Part Number Alternate Model or
Part Number
Spectrum analyzer 8565E
856xE
a
a. Must be capable of measuring a signal at 1 GHz.