Chapter 4
55
Service
Theory of Operation
Theory of Operation
The theory of operation begins with a general description of the 87075C Option H08
multiport test set. This is followed by more detailed operating theory. The operation of
each group is described briefly but only to the assembly level. Detailed component level
circuit theory is not provided.
System Theory
The test set consists of four main components: a power supply, a controller board, a front
panel display, and a main switch board. The purpose of the power supply is to provide
power to the other three assemblies. The front panel display serves to indicate the
switching paths to the user. The main switch board contains the switches and RF cabling.
Finally, the controller board does the actual switching between the different ports.
A1 Power Supply Theory
The switching power supply provides regulated DC voltages to power all assemblies in
the test set. A DC cable provides power to the main switch board. A connector from the
main switch board to the front panel display provides DC power and control signals to the
front panel. The power supply provides the following supplies: +5 V, +15 V, and -15 V.
A2 Front Panel Display Theory
The front panel display consists of 16 LEDs. Each test port has two LEDs associated with
it: one for reflection and one for transmission. Control signals and DC power are provided
by a cable connected to the main switch board.
A3 Main Switch Board Theory
Refer to
Figure 4-1
for the following discussion.
The main switch board contains all of the switches. A particular test port (1 through 8)
can be in one of three states. The three states are:
1. switched to the reflection port
2. switched to the transmission port
3. terminated in 75
Ω
Summary of Contents for 87075C Option H08
Page 1: ...Agilent Technologies 87075C Option H08 User s and Service Guide ...
Page 2: ......
Page 6: ...4 User s and Service Guide Supplement ...
Page 9: ...7 1 General Information ...
Page 22: ...20 Chapter1 General Information Performing the Operator s Check ...
Page 23: ...21 2 Controlling the Test Set and Making Measurements ...
Page 38: ...36 Chapter2 Controlling the Test Set and Making Measurements Calibrating the Test System ...
Page 39: ...37 3 Front Rear Panel ...
Page 45: ...43 4 Service ...
Page 60: ...58 Chapter4 Service Theory of Operation ...
