Keysight CXG, EXG, and MXG X-Series Signal Generators Service Guide 153
Troubleshooting
Amplitude Modulation Issues (Option UNT)
If the measured voltage is greater than or equal to 2.5 Vpp replace the A7
Micro Deck assembly.
14.Run the following adjustment:
AM Calibration
If the failure persists after the adjustment replace the A3 RF assembly.