Keysight Technologies N9040B UXA Manual page 21

Making Noise Figure Measurements
Making Frequency Converter Measurements
For both calibration and the measurement, a noise source, such as the
Keysight 346C, or the Keysight N4002A SNS, must be connected to the noise
source drive connector on the back of the X-Series analyzer. In this section, a
Keysight SNS series noise source is used as an example.
External LO control is used to control a signal generator to supply an LO at a
frequency range of 3.14 GHz to 3.64 GHz, and the frequency reference of the
signal generator may be connected to the EXT REF IN on the rear panel of the
X-Series analyzer. This locks the LO and the analyzer together for greater
measurement accuracy.
Figure 2-3 X-Series Frequency Converting DUT Measurement
N9069C Noise Figure Measurement Guide 21