Cobra 19 Plus User Manual

TABLE OF CONTENTS
Model 19 Plus
DESCRIPTION PAGE NUMBER
OPERATING THEORY- PLL FREQ. SYNTHESIZER....................................................................1-4
FREQUENCY CHART (TABLE 1)....................................................................................... . ..................5
BLOCK DIAGRAM..................................................................................................................................... 6
PLL CIRCUIT BLOCK DIAGRAM ............................. . ............................................................................7
ALIGNMENT PROCEDURE ................ 8-11
TEST EQUIPMENT SET-UP ................................................ 12
VOLTAGE CHART, IC’S & TRANSISTORS................................................... ..................................... 13
PARTS LAYOUT, PCB401068-F, TOP VIEW.......................................................................................14
COMPOSITE LAYOUT, PCB401068-F, TOP VIEW............................... . ......................................... 14
COMPOSITE LAYOUT, PCB 401377-C, 401261-B, TOP VIEW ........................................................ 14
PARTS LAYOUT, PCB401068-F, BOTTOM VIEW ........... .. .................................................................15
PARTS LAYOUT, PCB 401377-C, 401261-B, BOTTOM VIEW............................................................15
COMPOSITE LAYOUT, PCB401068-F, BOTTOM VIEW.....................................................................16
COMPOSITE LAYOUT, PCB 401377-C, 401261-B, BOTTOM VIEW...................................................16
COPPER PATTERN, PCB401068-F, BOTTOM VIEW.........................................................................17
COPPER PATTERN, PCB 401377-C, 401261-B, BOTTOM VIEW.......................................................17
WIRING DIAGRAM, CHASSIS & MIC PINS..........................................................................................18
PCB 401068-D WIRING DIAGRAM.........................................................................................................19
SEMICONDUCTOR PIN CONFIGURATION..........................................................................................20
I.C. DIAGRAMS, LM6416E, LC7131, TA7310P.....................................................................................21
I.C. DIAGRAMS, KIA7217AP, TL489CP, MC78L08CT ........................................................................... 22
EXPLODED VIEW PARTS LIST.............................................................................................................23
EXPLODED VIEW ................................................ 24
SCHEMATIC DIAGRAM..................................................................................................... 25
PARTS LIST........................................................ 25

Cobra 19 Plus Specifications

General

Type	CB Radio
Channels	40
Power Output	4 Watts
Modulation	AM
Microphone	Dynamic
Frequency Range	26.965-27.405 MHz
RF Output Power	4 Watts
Modulation Type	AM
Speaker	Built-in
Power Source	12V DC

Summary

OPERATING THEORY OF PLL FREQUENCY SYNTHESIZER

Fundamental PLL Circuitry Theory

Basic PLL circuit components and function.

CIRCUIT DESCRIPTIONS AND DIAGRAMS

Transmitter Circuit Overview

Details on mixer, amplifier, RF power driver, and modulation circuits.

Receiver Circuit Overview

Explanation of receiver operation and components.

Channel Selection Control

Microprocessor control for channel selection and scanning.

System Block Diagrams

Overall system and PLL circuit block diagrams.

ALIGNMENT PROCEDURES

PLL Circuit Alignment

Procedures for checking the 10.24MHz oscillator and VCO.

Transmitter Alignment Steps

Test setup, RF amp alignment, frequency, and modulation adjustments.

Receiver Alignment Steps

Test setup, sensitivity, and squelch circuit adjustments for the receiver.

COMPONENT DETAILS AND VIEWS

Exploded View Part List

Detailed list of parts with numbers and descriptions.

Exploded View Diagram

Visual representation of component assembly.

Schematic Diagram

Detailed electronic schematic of the device.

Parts List Details

Comprehensive list of all parts used in the Model 19 Plus.