Motorola CP 140 Informazioni sul servizio - Pagina 9

Sfoglia online o scarica il pdf Informazioni sul servizio per Radio portatile Motorola CP 140. Motorola CP 140 46. Uhf2 (438-470mhz)
Anche per Motorola CP 140: Manuale d'uso (26 pagine), Manuale d'uso di base (16 pagine), Manuale d'uso di base (16 pagine), Manuale d'uso di base (18 pagine), Manuale di servizio dettagliato (28 pagine), Manuale di installazione di Cps/Tuner (6 pagine), Informazioni sul servizio (46 pagine)

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 (438-470MHz) Receiver

The UHF receiver covers the range of 438-470 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