4-42 Service Guide N5227-90001
Troubleshooting PNA Series Microwave Network Analyzers
Measurement System Troubleshooting N5227A
3. If the measured signal is not present, replace the A37 reference mixer switch. Refer to “Removing and
Replacing the A37 Reference Mixer Switch” on page 7-36.
Checking the A46, A47, A48, and A49 35-dB Receiver Step Attenuators
1. Locate the appropriate semirigid cable at the output of the receiver step attenuator to be checked:
• Options 219, 224, 419, and 423
— Port 1; W98 of A46
— Port 2; W104 of A49
— Port 3; W100 of A47
— Port 4; W102 of A48
2. Disconnect the appropriate semirigid cable from the output of the step attenuator.
3. Connect the spectrum analyzer to the open step attenuator connector. Set the spectrum analyzer to
measure a signal at 800 MHz.
4. If the 800 MHz signal is not present, replace the receiver step attenuator. Refer to “Removing and
Replacing the A38–A41 Source Attenuators and the A46–A49 Receiver Attenuators” on page 7-38.
5. If the 800 MHz signal is present, replace the associated mixer brick, A27 or A28. Refer to “Removing and
Replacing the A27 and A28 Mixer Bricks” on page 7-30.
Checking the A24 IF Multiplexer Board
1. Locate each of the flexible RF cables at the output receivers of the IF multiplexer board:
•2-port models
— Receiver A; W69
— Receiver R1; W72
— Receiver R2; W73
— Receiver B; W70
•4-port models
— Receiver A; W69
— Receiver B; W70
— Receiver C; W72
— Receiver D; W73
— Receiver R; W71
2. Disconnect the appropriate flexible RF cable from the output receiver to be tested on the A24 IF
multiplexer board.
3. Connect the spectrum analyzer to the open connector.
4. Refer to the IMPORTANT notice on page 4-23. The measured signal on the spectrum analyzer should be
at 7.61 MHz (analyzers with DSP version 4.0), or 7.44 MHz (analyzers with DSP version 5.0), and 1 GHz
.
5. If the measured signal is present, replace the A16 SPAM board. Refer to “Removing and Replacing the
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