Keysight M9383B Measurement Manual page 16

Basic Measurements
Making Measurements
6. Close the Vector Modulation Signal Setup.
7. Ensure that RF Out is on.
On the N9040B:
1. Select Frequency and set Center Frequency to 20 GHz and Span to 
2. Select BW and set Res BW to 100 Hz.
16
Selecting Enable Vector Modulation Signal automatically turns on both
Output Modulation and Internal I/Q Modulation.
500 kHz.
M9383B/84B Measurement Guide