Motorola MCS 2000 Service Instructions Manual page 13

Theory of
Operation
Introduction
Revision B, 5/98
This chapter provides theory of operation information for the radio. It
starts with a block diagram level functional description of the entire
radio. This is followed by a detailed functional description for each of
the four major functions of the radio.
The radio is composed of the following four major functions:
• Receiver
• Transmitter
• Dc Power Control and Regulation
• Operator Interface (Control Head)
The receiver, transmitter, and dc power control and regulation
functions are all located on a single circuit card assembly (CCA) in the
main body of the radio. The CCA is called the transceiver board. The
operator interface function consists of the control head, which plugs
into the main body of the radio. There are three different control head
types: the Model I for the Model I Radio; the Model II for the Model II
Radio; and the Model III for the Model III Radio. The three control
heads are covered in their entirety in Volume 1 of this service manual.
The transceiver board in the main body of the radio is physically
separated into six functional sections as follows:
• Receiver Front End
• Receiver Intermediate Frequency (IF)
• Receiver Back End
• Power Amplifier (PA)
• Synthesizer
• Controller
The controller section is further divided into two sub-sections: main
controller; and power control. The mechanical layout of the
transceiver board is illustrated in Chapter 4.
Separate component location diagrams, parts lists, and schematic
diagrams are provided in this service manual for each of the six
physical sections of the transceiver board and for the control heads.
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Theory of Operation 5