Rf Assembly Description; Purpose - Keysight N9000A Service Manual

RF Assembly Description

Purpose

There are various optional frequency ranges that can be ordered with the N9000A,
Signal Analyzer.
• Option 503, 3.0 GHz Frequency Range
• Option 507, 7.5 GHz Frequency Range
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 ≤ 3.0 GHz
2. High band RF path is used when the input frequency is > 3.0 GHz to 7.5 GHz
The RF board have both RF section and AIF section. The RF section is designed to
convert RF input signals to an intermediate frequency of 322.5 MHz. Then a
switch to high-band and low-band merged together. Signal entered AIF section.
The AIF section provides gain to compensate for the loss of the second mixer and
adjust the IF output level to ADC in DIF. It down converts the second IF frequency
322.5 MHz to the third IF frequency 22.5 MHz with the appropriate gain and
filtering. The AIF section also provides RF Triggering.
1. When tuned below 3.0 GHz, the RF section up-converts the signal to low band
first IF of 3947.5 MHz and then down converts to second IF of 322.5 MHz with
the appropriate filtering and switchable preamplifier. The image and
out-of-band responses will be eliminated by the low band pass filter.
2. When tuned in the high band (3 GHz to 7.5 GHz), the RF section down
converts the signal to high band first IF of 1228.75 MHz and then down
converts to second IF of 322.5 MHz with the appropriate filtering and
switchable preamplifier. The image and out-of-band responses will be
eliminated by the six groups of preselector filters. HA
Inputs to the RF assembly
st
• 1 LO Input (from the A9 L.O. Assembly)
rd
• 3 LO Input (from the A9 L.O. Assembly)
• 100 MHz reference signal (from the A9 L.O.Assembly)
• Signal Input (from the Signal Input Connector)
• 50 MHz Cal signal (from the A9 L.O. Assembly)
Outputs from the RF assembly
• 22.5 MHz signal (to A2 Digital I.F. Assembly)
• AUX IF Output (to Rear Panel)
Chapter 4
RF Section Troubleshooting
RF Assembly Description
127