Keysight N9038A, Руководство по обслуживанию

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384 Keysight N9038A MXE Service Guide
Optional Assemblies
A25 Wideband Analog IF Assembly Description
A25 Wideband Analog IF Assembly Description
A25 Wideband Analog IF Assembly Purpose
The A25 Wideband Analog IF assembly's primary role is to properly filter and
apply attenuation or gain to optimize the level going to the Analog to Digital
Converter (ADC) and provide sufficient pre-filtering to reject images that would
otherwise interfere with the signals of interest. Precision alignments are used to
calibrate the filters, attenuators and gain of this assembly.
A25 Wideband Analog IF Assembly Description
The input signal of the instrument is down converted to a 300 MHz
intermediate frequency by the A13 Front End assembly and routed through the
A15 Front End Controller to the input of the A25 Wideband Analog IF at J101.
The signal is then filtered, with attenuation or gain being applied based upon
the instrument settings. This signal is then sampled by the ADC and the
resultant data is sent to the A26 Wideband Digital IF assembly for processing.
IF Signal Routing
The wideband IF output of the A15 Front End Controller J901 is routed to the
A25 Wideband Analog IF via W52. Without the optional 85 MHz analysis
bandwidth option (B85) this signal would go directly to the A3 Digital IF
assembly. In order to accommodate both the A25 Wideband Analog IF and the
A3 Digital IF assemblies the signal is routed to the A25 Wideband Analog IF
assembly which can either use the signal itself or route it back out to the A3
Digital IF assembly when needed.
The frequency of the signal input at J101 is 300 MHz when the A25 Wideband
Analog IF assembly is going to use it, and it is 250 MHz when it is to be routed
back out to the A3 Digital IF assembly.
Clock and Calibrator Signals
Using the 2400 MHz calibration signal coming to J301 from the A16 Reference
assembly the A25 Wideband Analog IF assembly generates other needed clock
and calibration signals used by both this assembly and others.
RF Burst Trigger
The A25 Wideband Analog IF assembly also generates a built in RF Burst
Trigger that is available when the 85 MHz IF path is selected in IQ Analyzer
(Basic) mode.
Refer to Chapter 15, “Block Diagrams”