Measurement Group; A4 Rf Board - Agilent Technologies FieldFox N9923AN Service Manual

RF Vector Network Analyzer
N9923AN

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:
•

A4 RF Board

• A5 System Board
• A6 SOM Board
• Main Battery
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
10 49.607
11 50.000
a. Except for band 1, start frequency is previous stop frequency +0.001 Hz.
Service Guide N9923-90005
a
Stop Frequency
Band Start Frequency
(MHz)
2.732 12
3.125 13
5.875 14
6.250 15
12.107 16
12.500 17
24.607 18
25.000 19
49.607 20
50.000 21
99.607
Figure 5-2..
Figure 5-3.
a
Stop Frequency
(MHz)
99.607
100.000
199.750
399.900
800.000 1600.000
1600.000 3200.000
3200.000 3399.000
3399.000 4149.705
4149.705 5099.705
5099.705 6000.000
Theory of Operation
Measurement Group
(MHz)
100.000
199.750
399.900
800.000
5-7