Cobra 19DX IV Service Manual

A1
English
Our Thanks and
Customer Assistance
Introd uctio n
Thank you for purchasing the Cobra 19 DX IV EU CB Radio
Transceiver. Properly used, this Cobra product will give
you many years of reliable service.
NOTICE!
Before using this transceiver, please check that the radio has been programmed on the
frequency band specifications and operating modes allowed by the regulations valid in the
country where the product is used. If not, please proceed to modify the frequency band
programming, as described in this owners manual page 5. This transceiver is programmed at
the factory on the EU frequency band (40 CH AM 1W/40 CH FM 4W).
Customer Assistance
Should you encounter any problems with this product, or not understand
its many features, please refer to this owner’s manual. If you require further assistance after
reading this manual, please contact your local dealer.
This equipment is intended for use in:
For Warranty, Product Service and
Accessory Information
Please contact your local dealer or distributor.
See the enclosed leaflet that provides contact
information for the Cobra international
distributors.
Customer Assistance
©2009 Cobra Electronics Corporation
6500 West Cortland Street
Chicago, Illinois 60707 USA
www.cobra.com
M O BILE RADIO
19 DX IV EU
Printed in China
Part No. 480-526-P
Version C
Nothing Comes ClosetoaCobra
®
English
Nothing Comes Close toa Cobra
®
English
For more information or to
order any of our products,
please visit our website:
www.cobra.com
CB Radios
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®
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The Cobra line of quality products includes:
AT
BA
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CH
CZ
DE
This equipment is intended for use in:
Countries of use
EE
ES
FI
FR
GB
GR
HR
HU
A
IE
IS
IT
NL
NO
PT
RO
RS
SE
SI
SK
TR
LT
LV
LU
DK
MK
MT
CY
UA
RU
PL

Cobra 19DX IV Specifications

General

Channels	40
Modulation	AM
Power Output	4 Watts
Antenna Impedance	50 Ohms
Power Supply	13.8 VDC
Weight	2.5 lbs
Frequency Range	26.965 MHz to 27.405 MHz

Summary

Introduction and Customer Assistance

Customer Support Information

Details on how to get assistance and warranty, product service, and accessory information.

Product Specifications

General Receiver Specifications

General Transmitter Specifications

Technical Description

General Overview and Controls

Frequency Control Circuitry

Basic Synthesis Scheme

Detailed Circuit Description

Synthesizer Implementation Details

Programmable Divider and Phase Detector

Reference Frequencies and VCO

Transmitter RF Amplification

Frequency Stability

Discusses factors affecting frequency stability, including crystal and component selection.

Spurious Radiation Suppression

Modulation Control

Transmitter Tune-Up Procedure

Preliminary Synthesizer Alignment

Procedure for preliminary alignment of the synthesizer, including voltage adjustments.

TX Alignment Steps

Details the alignment steps for the transmitter section, focusing on RF signal measurement.

Final Alignment Procedures

Describes the final alignment steps for the receiver section.

Final Transmission Check

Outlines the final checks for output power, frequency, and spurious signals.

Troubleshooting Hints

Common Issues and Solutions

Provides a table listing common symptoms, probable causes, and remedies for troubleshooting.

Test Equipment and Alignment Instructions

RX VCO and Frequency Adjustment

Instructions for aligning the RX VCO voltage and frequency using test equipment.

TX VCO Adjustment

Instructions for adjusting the TX VCO voltage and confirming its range.

Transmitter Alignment

Modulation Adjustment

Procedure for adjusting modulation levels and checking deviation limits.

RF Power Confirmation

Steps to confirm the RF power output of the transmitter.

Receiver Alignment

RX Sensitivity and Squelch Adjustment

Procedure for adjusting RX sensitivity, squelch, and audio output levels.

Semiconductor Identification

Integrated Circuits (ICs)

Transistors

Diodes

Voltage Charts

IC Voltage Readings

Provides voltage charts for specific ICs (CPU, KIA7217, TB31202FN) in RX and TX modes.

Transistor Voltage Readings (Receive/Transmit)

Transistor Voltage Readings

Lists voltage readings for transistors in both receive and transmit modes.