Motorola CP 140 Service Information - Page 9

Browse online or download pdf Service Information for Two-Way Radio Motorola CP 140. Motorola CP 140 46 pages. Uhf2 (438-470mhz)
Also for Motorola CP 140: User Manual (26 pages), Basic User's Manual (16 pages), Basic User's Manual (16 pages), Basic User's Manual (18 pages), Detailed Service Manual (28 pages), Cps/Tuner Installation Manual (6 pages), Service Information (46 pages)

Print Page

1.0

This Chapter provides a detailed theory of operation for the UHF circuits in the radio. Schematic

diagrams and board layout diagrams are included in Chapter 4 in this Section of the manual.

2.0

UHF (465-495MHz) Receiver

The UHF receiver covers the range of 465-495 MHz and provides switchable IF bandwidth for use

with 20/25/30 kHz or 12.5 kHz channel spacing systems. The receiver is divided into two major

blocks, as shown in Figure 2-1.

Front End

Back End

RX from

Antenna Switch

Preselector

Filter

Amp

First LO

from Synthesizer

Recovered Audio

RSSI

Figure 2-1 UHF Receiver Block Diagram

THEORY OF OPERATION

Interstage

Crystal

Filter

1st Mixer

Inj Filter

Ceramic

Resonator

Demodulator

12.5kHzFilter

Chapter 2

Amp

Filter

BW_SEL

Cer Fltr

Switching