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This product complies with the RoHS directive for the European market.
This product uses Lead Free solder.
SERVICE MANUAL
© 2012-9 PRINTED IN JA PAN
B53-7033-00 (Y) 672
NX-820H(G)/820H
UHF DIGITAL TRANSCEIVER
CONTENTS
Panel assy
(A62-1200-03)
Badge
(B43-1675-04)
Key top
(K29-9479-01)
Modular jack
(E58-0535-05)
GENERAL ....................................................2
SYSTEM SET-UP .........................................4
REALIGNMENT ...........................................4
INSTALLATION ............................................7
DISASSEMBLY FOR REPAIR .....................9
CIRCUIT DESCRIPTION ...........................11
COMPONENTS DESCRIPTION ................17
PARTS LIST ...............................................19
EXPLODED VIEW ......................................29
PACKING ...................................................30
TROUBLE SHOOTING ..............................31
ADJUSTMENT ...........................................35
TERMINAL FUNCTION .............................56
PC BOARD
DISPLAY UNIT (X54-3830-10) ...............60
TX-RX UNIT (X57-8240-1X)....................62
INTERCONNECTION DIAGRAM ...............66
SCHEMATIC DIAGRAM ............................67
BLOCK DIAGRAM .....................................78
LEVEL DIAGRAM ......................................81
OPTIONAL ACCESSORIES
KRA-40 ..................................................82
SPECIFICATIONS .................BACK COVER
NX-820H(G)/820H
2
INTRODUCTION
SCOPE OF THIS MANUAL
This manual is intended for use by experienced techni-
cians familiar with similar types of commercial grade com-
mu ni ca tions equipment. It contains all required service
in for ma tion for the equipment and is current as of the pub-
lication date. Changes which may occur after publication
are covered by either Service Bulletins or Manual Revisions.
These are is sued as required.
ORDERING REPLACEMENT PARTS
When ordering replacement parts or equipment informa-
tion, the full part identifi cation number should be included.
This applies to all parts : components, kits, or chassis. If the
part number is not known, include the chassis or kit number
of which it is a part, and a suffi cient description of the re-
quired component for proper identifi cation.
PERSONAL SAFETY
The following precautions are recommended for personal
safety:
• DO NOT transmit if someone is within two feet (0.6 me-
ter) of the antenna.
• DO NOT transmit until all RF connectors are secure and
any open connectors are properly terminated.
• SHUT OFF this equipment when near electrical blasting
caps or while in an explosive atmosphere.
• All equipment should be properly grounded before pow-
erup for safe operation.
• This equipment should be serviced by only qualifi ed tech-
nicians.
PRE-INSTALLATION CONSIDERATIONS
1. UNPACKING
Unpack the radio from its shipping container and check
for accessory items. If any item is missing, please contact
KENWOOD immediately.
2. PRE-INSTALLATION CHECKOUT
2-1. Introduction
Each radio is adjusted and tested before shipment. How-
ever, it is recommended that receiver and transmitter opera-
tion be checked for proper operation before installation.
2-2. Testing
The radio should be tested complete with all cabling and
accessories as they will be connected in the fi nal installation.
Transmitter frequency, deviation, and power output should be
checked, as should receiver sensitivity, squelch operation,
and audio output. Signalling equipment operation should be
verifi ed.
3. PLANNING THE INSTALLATION
3-1. General
Inspect the vehicle and determine how and where the ra-
dio antenna and accessories will be mounted.
Plan cable runs for protection against pinching or crush-
ing wiring, and radio installation to prevent overheating.
3-2. Antenna
The favored location for an antenna is in the center of a
large, flat conductive area, usually at the roof center. The
trunk lid is preferred, bond the trunk lid and vehicle chassis
using ground straps to ensure the lid is at chassis ground.
GENERAL
Document Copyrights
Copyright 2012 by JVC KENWOOD Corporation. All
rights reserved.
No part of this manual may be reproduced, translated,
distributed, or transmitted in any form or by any means,
electronic, mechanical, photocopying, recording, or other-
wise, for any purpose without the prior written permission of
JVC KENWOOD Corporation.
Disclaimer
While every precaution has been taken in the preparation
of this manual, JVC KENWOOD Corporation assumes no
responsibility for errors or omissions. Neither is any liability
assumed for damages resulting from the use of the informa-
tion contained herein. JVC KENWOOD Corporation reserves
the right to make changes to any products herein at any time
for improvement purposes.
Firmware Copyrights
The title to and ownership of copyrights for firmware
embedded in KENWOOD product memories are reserved
for JVC KENWOOD Corporation. Any modifying, reverse
engineering, copy, reproducing or disclosing on an Internet
website of the firmware is strictly prohibited without prior
written consent of JVC KENWOOD Corporation. Further-
more, any reselling, assigning or transferring of the fi rmware
is also strictly prohibited without embedding the fi rmware in
KENWOOD product memories.
Transceivers containing AMBE+2™ Vocoder:
The AMBE+2™ voice coding technology is embedded in
the fi rmware under the license of Digital Voice Systems, Inc.
NX-820H(G)/820H
3
3-3. Radio
The universal mount bracket allows the radio to be
mounted in a variety of ways. Be sure the mounting surface
is adequate to support the radio’s weight. Allow sufficient
space around the radio for air cooling. Position the radio
close enough to the vehicle operator to permit easy access
to the controls when driving.
3-4. DC Power and wiring
1. This radio may be installed in negative ground electrical
systems only. Reverse polarity will cause the cable fuse
to blow. Check the vehicle ground polarity before installa-
tion to prevent wasted time and effort.
2. Connect the positive power lead directly to the vehicle
battery positive terminal. Connecting the Positive lead to
any other positive voltage source in the vehicle is not rec-
ommended.
3. Connect the ground lead directly to the battery negative
terminal.
4. The cable provided with the radio is suffi cient to handle
the maximum radio current demand. If the cable must be
extended, be sure the additional wire is suffi cient for the
current to be carried and length of the added lead.
4. INSTALLATION PLANNING – CONTROL STATIONS
4-1. Antenna system
Control station. The antenna system selection depends
on many factors and is beyond the scope of this manual.
Your KENWOOD dealer can help you select an antenna sys-
tem that will best serve your particular needs.
4-2. Radio location
Select a convenient location for your control station radio
which is as close as practical to the antenna cable entry
point. Secondly, use your system’s power supply (which sup-
plies the voltage and current required for your system). Make
sure suffi cient air can fl ow around the radio and power sup-
ply to allow adequate cooling.
SERVICE
This radio is designed for easy servicing. Refer to the
schematic diagrams, printed circuit board views, and align-
ment procedures contained in this manual.
NOTE
If you do not intend to use the speaker 3.5-mm jack and
the D-sub 15-pin connector, fi t the supplied speaker-jack cap
and ACC cap to stop dust and sand from getting in.
ACC.
Speaker
jack cap
Power input
connector
Antenna
connector
ACC. cap
SMA
W/GPS Type
only
GENERAL
