Measurement Group; A4 Rf Board - Keysight N9923A Service Manual

Theory of Operation

Measurement Group

Measurement Group
The measurement group produces a stable output signal by phase locking a
synthesized voltage-controlled oscillator (VCO).
The measurement group consists of the:
—
—
—
—
A simplified RF block diagram is provided in
A simplified system block diagram is provided in

A4 RF Board

The basic function of the A4 RF board is to provide a signal source and
receivers for the analyzer functions.
An LO synthesizer produces a single LO signal from the 30 MHz time base
located on the A5 system board. The LO output is delivered to the NA mixers of
both ports.
The LO frequency is always above the measured frequency. The IF is 390 kHz.
The 30 MHz time base is also used to generate a source signal in the source
synthesizer that covers the frequency range of 2 MHz to 6 GHz.
The source signal is generally rich in harmonic content. This is acceptable
because the signal is used with tuned receivers.
The frequency bands for the RF board are listed below:
Band
Start Frequency
(MHz)
1 2.000
2 2.732
3 3.125
4 5.875
5 6.250
6 12.107
7 12.500
8 24.607
9 25.000
5-6
A4 RF Board
A5 System Board
A6 SOM Board
Main Battery
Stop Frequency
a
(MHz)
2.732
3.125
5.875
6.250
12.107
12.500
24.607
25.000
49.607
Figure 5-2.
Figure
Band
a
Start Frequency
(MHz)
12 99.607
13 100.000
14 199.750
15 399.900
16 800.000
17 1600.000
18 3200.000
19 3399.000
20 4149.705
Keysight N9923A Service Guide
5-3.
Stop Frequency
(MHz)
100.000
199.750
399.900
800.000
1600.000
3200.000
3399.000
4149.705
5099.705