196 Keysight N9038A MXE Service Guide
RF Preselector Section
RF Preselector Section Troubleshooting
Synchronization in Chapter 19, “Post-Repair Procedures”. If this LED is always
on there is most likely a problem with the 10 MHz reference signal to the FPGA
chip.
Fixed Frequency Mode
This LED should be on whenever the RF Preselector is turned on and the
instrument span is set to 0 Hz.
Swept Mode
This LED should be on whenever the RF Preselector is turned on and the
instrument span is greater than 0 Hz.
Stepped Mode
This LED should be on whenever the RF Preselector is turned on and the
instrument is in stepped mode. The only way to place the instrument in
stepped mode is with the use of the EMI Receiver mode. This is accessed by
pressing Mode, EMI Receiver, Meas Setup, More, Scan Type, Discrete, then
press Restart to start the stepped mode.
Signal Path Verification
There are seven different filtered signal paths and one through path on the A22
Radiated Filter assembly, all of which can be selected with the use of the
instrument's Service Menu. This section will describe how to verify the
functionality of all eight signal paths.
1. Remove the instrument dress cover (MP24) and the top brace (MP10).
Refer to Chapter 18, “Assembly Replacement Procedures” for instructions
on removing these covers.
2. Referring to Figure 5-4 and Figure 5-5, remove W34 and W35 from the
A22 Radiated Filter assembly.
To remove W35 pinch the retainer clips on both ends of the cable and
slide the retainers away from the connection as shown in Figure 5-21.
Only one of the Fixed Frequency Mode, Swept Mode, and Stepped Mode LEDs should ever be on
at the same time.
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