Keysight Technologies FieldFox N9913A Service Manual page 63

Theory of Operation
Measurement Group
The RF Out attenuator between the source and the reflectometer has three
settings: nominal values of 0 dB, 35 dB or user input value. The setting is
determined by the High, Low or Manual power setting on the user interface.
And beginning from firmware A.06.18, the default output power level is -15
dBm.
The reflectometer performs three functions:
— It passes the source output signal to either PORT 1 or PORT 2.
— It samples the source output to either PORT 1 or PORT 2.
— It samples the incoming signal at either PORT 1 or PORT 2.
The sampled signals are mixed with the LO signal to produce three 390 kHz IF
signals, NA-A, NA-B and NA-R.
The reflectometer dissipates up to 1.5 watts when active.
Each port (PORT 1 and PORT 2) has a DC isolation capacitor.
Keysight FieldFox Handheld Analyzers Service Guide 63