Rf Section Description; Purpose - Keysight N8973B Service Manual

RF Section Troubleshooting (N8973B, 74B, 75B Analyzers)

RF Section Description

RF Section Description

Purpose

This section covers only those model numbers listed below for the NFA Series
Noise Figure Analyzers.
— N8973B (10 MHz - 3.6 GHz)
— N8974B (10 MHz - 7 GHz)
— N8975B (10 MHz - 26.5 GHz)
— N8976B (10 MHz - 40 GHz)
The RF input signal can be routed through three different front end signal
paths. These various paths are switched in and out based on where the signal
analyzer center frequency is tuned.
1. Low band RF path is used when the input frequency is ≤ 3600 MHz
2. High band RF path #1 is used when the input frequency is > 3.6 GHz to
3. High band RF path #2 is used when the input frequency is > 13.6 GHz to
The RF section is designed to convert RF input signals to an intermediate
frequency (IF) that is present at the RF output of the A13 Front End assembly.
This IF depends on installed options and the IF path selected. This chapter will
assume the analyzer is in Spectrum Analyzer mode. Therefore, the IF will be
322.5 MHz.
IF Path
10 MHz (standard)
25 MHz (Option B25)
134
13.6 GHz
26.5 GHz
IF
322.5 MHz
322.5 MHz
Mode
Spectrum Analyzer or
IQ Analyzer
IQ Analyzer
Keysight NFA Series Noise Figure Analyzers Service Guide