A14 L.o. Synthesizer Assembly Description; Purpose - Keysight n9020a Service Manual

L.O. Synthesizer/Reference Troubleshooting

A14 L.O. Synthesizer Assembly Description

A14 L.O. Synthesizer Assembly Description

Purpose

The L.O. Synthesizer assembly provides the 1st Local Oscillator to the A13 RF
Front End Assembly for RF conversion. This assembly has the following inputs
and outputs:
— Power Supply inputs
— Serial Bus input for L.O. Control
— Sweep input for L.O. Control
— 4800 MHz input signal from A16 Reference Assembly
— 1st L.O. output signal to A13 RF Front End Assembly
The input signal to the L.O. Synthesizer Assembly is a 4800 MHz signal that is
generated on the A16 Reference Assembly. The 1st L.O. is then phase locked
to this 4800 MHz reference, which is then phase locked back to the 10 MHz
reference located on the A16 Reference Assembly. The quality of the phase
lock design that locks the 1st L.O. has a direct relationship on the overall
stability of the analyzer. Users can also provide their own external reference.
The frequency accuracy of the user frequency reference is directly related to
the overall frequency accuracy of the signal analyzer.
The 1st L.O. has a tuning range from 3.8 GHz to 8.7 GHz and an output power
from +13 to +18 dBm. The RF input signal mixes with the 1st L.O. in one of
three possible mixers on the RF Front End Assembly. For more detailed
description on the RF Front End Assembly, see Chapter 4, "RF Section
Troubleshooting" in this service guide.
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