A16 Reference Assembly Description; Purpose - Keysight n9020a Service Manual

L.O. Synthesizer/Reference Troubleshooting

A16 Reference Assembly Description

A16 Reference Assembly Description

Purpose

The A16 Reference Assembly provides the fundamental reference signals from
which all instrument local oscillator and synchronous timing signals are
derived The reference board also uses these same signals to generate CW and
modulated RF calibration signals and a 10 MHz time base signal for the
instrument
For analyzers with serial prefixes ≥ MY/SG/US5233, or any with Option B85,
B1A, or B1X the Reference assembly must be replaced as a single assembly,
although it is constructed of two boards, the A16 Reference Main board and
A16A1 Reference Daughter board. These boards are listed individually in the
Show Hardware screen, allowing identification of the individual board part
numbers comprising the complete assembly.
The reference signals and local oscillators can be phase locked to a timebase
in one of two ways:
1. The internal 10 MHz reference located on the A16 Main Board.
2. An externally provided reference such as a house standard or the reference
If an external reference signal is within 200 Hz of the specified external
reference frequency and Freq Ref In is set to Sense, the analyzer will
automatically switch from SENSE:INT to SENSE:EXT.
The frequency accuracy of the analyzer is directly tied to the accuracy of the
frequency reference that is being used.
Diagnostic LEDs monitor the status of the various PLLs on the A16 Reference
Assembly.
from another instrument or a base transceiver system. The external
reference can be any RF signal in the range of 1 MHz to 50 MHz, -5 dBm to
+10 dBm.
290