RELM BK RADIO SDMX920 User manual

Base Station and Repeater
SMX920
SDMX920
VER. 1.1.4
0300-30973-700_REV 07-14

Technical Manual
MX920 Base Station & Repeater
i
© SPECTRA ENGINEERING 2003 Revision 1.1.4
RELM
Wireless C o r por a t ion
7100 Technology Drive
West Melbourne, FL 32904
Front Desk: (321)
984-1414
Sales: [phone]
Service: (800)
422-6281
www.RELM.com
In order to continually improve our products, Spectra Engineering Pty Ltd reserves the right to
alter, without notice and at any time, the equipment and specifications described in this
document.
All performance figures quoted are typical and are subject to normal manufacturingand
service tolerances.
The purchaser is warned that some statements made in this document may be inaccurate due to
typographical or other errors or subsequent modifications of the product. While every care has
been taken in the creation of this document, no warranty of accuracy or reliability is given, in
any advice or information contained in this document. Spectra Engineering Pty Ltd or any
director, officer, agent or employee of Spectra Engineering Pty Ltd cannot be held liable
for any
loss or damage whatsoever arising in any way or any representation,act or omission whether
express or implied (including responsibility to any person by reason of negligence).
Copyright © Spectra Engineering Pty Ltd 1997
This work is copyright. Other than as permitted by Law, no part of it may be reproduced,
stored in a retrieval system or transmitted in any form or by any process without prior written
permission.
FCC Interference
Warning
Note: The equipment has been tested and found to comply with the limits for a class B digital
device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference when the equipment is operated in a commercial or
residential environment. This equipment generates, uses and can radiate radio frequency
energy. If not installed and used in accordance with this instruction manual, may
cause
harmful
interference to radio communication.

MX920 Base Station & Repeater
Technical Manual
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© SPECTRA ENGINEERING 2003 Revision 1.1.4
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Technical Manual
MX920 Base Station & Repeater
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© SPECTRA ENGINEERING 2003 Revision 1.1.4
Record Of Changes
Any changes to this manual are recorded on this list. Spectra Engineering may issue
replacement pages to you from time to time. If any updates are issued, you will also
receive a replacement for this page.
Date Version Chapter Changes Pages Changed
Mar 2003 1.0.0 All - Initial Release All
June 2004 1.1.0 General Revision All
Sept 2004 1.1.1 Changes to Table 8-4 Rs232 Pin
configuration 33
19/10/06 1.1.2 Added Screw Head Types section
2.2 8
22/01/07 1.1.3 Updated RJ45 line level spec's 33
21/01/07 1.1.4 Updated Calibration Section 7 29

MX920 Base Station & Repeater
Technical Manual
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© SPECTRA ENGINEERING 2003 Revision 1.1.4
SAFETY SUMMARY
Only the MX920’s self contained power supply, if installed, contains dangerous mains
voltages within. Normal operation and use of the MX920 does not expose the operator or
service technician to high voltage parts. The power supply is isolated from and maybe
removed safely from the main chassis. For servicing, please return to your nearest
distributor. No fuses or user-serviceable parts are within the power supply module.
The following general safety precautions as would normally apply, should be observed
during all phases of operation, service and repair of this equipment.
AROUND THE EQUIPMENT
To minimise any possible shock hazard from an external power supply or lightning strike, the
chassis or equipment cabinet must be connected to an electrical ground. This is normally
achieved by the Earth grounding wire within the 3 wire mains cable. Provide adequate
ventilation around the rear of the equipment.
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE
Do not operate the equipment in the presence of flammable gases or fumes. Operation of
any electrical equipment in such an environment constitutes a definite safety hazard.
DO NOT ATTEMPT INTERNAL SERVICE WHILE TRANSMITTING
Thermal or RF burns may result from touching certain components within the power
amplifier module while transmittingor operating the transmitter.
DO NOT SUBSTITUTE PARTS OR MODIFY THE EQUIPMENT
Because of the danger of introducingadditional hazards, do not install substitute or lower
voltage parts to the equipment. Return to your authorised distributor.
EXERCISE CAUTION AND CORRECT DISPOSAL OF RF POWER DEVICES Most
RF power transistors and some RF power hybrids contain Beryllium Oxide. Although they
are normally safe, if physically damaged toxic dust may be released. Consult your local
authority for correct disposal thereof. Such devices are not normally used in the MX920.
WARRANTY CONDITIONS & PRECAUTIONS
The following conditions are not covered by the warranty of the MX920. Please ensure that
the MX920 is not subject to;
1. Over voltage or Reverse Power Supply Voltage.
2. Operation in locations subject to abnormal environmental conditions such as extreme
temperatures or ingress of moisture or excessively dusty environments.
3. Operation of the MX920 Transmitter output into an open or short circuit or an incorrectly
terminated load. Although a level of VSWR protection is included, greater protection is
provided by the addition of a TX RF isolator.

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© SPECTRA ENGINEERING 2003 Revision 1.1.4
Technical Manual
Table of Contents
Table of Contents
1. General
Description........................................................................................... 1
1.1 Physical
Description.................................................................................. 2
1.1.1 Front Panel
.................................................................................. 3
1.2 Module Functional
Description ................................................................. 6
1.2.1 RF Module and Main Controller Assembly
................................. 6
1.2.2 Power Amplifier
Module.............................................................. 7
2. Installation and
Operation................................................................................ 8
2.1
Installation ................................................................................................. 8
2.2 Screw Head
Types..................................................................................... 8
2.3
Operation ................................................................................................... 9
2.3.1 Setting to
Work ............................................................................. 9
2.3.2
Adjustments ................................................................................ 11
3. Standard Features
........................................................................................... 12
3.1 Programmable Channel
Spacing ............................................................. 12
3.2 Programmable DCS / CTCSS encoder /
decoder .................................... 12
3.2.1
Description ................................................................................. 12
3.3 Local Speaker, Mic Socket and Front Panel Mute / Squelch Controls... 12
3.3.1
Description ................................................................................. 12
3.4 Local Channel Change
............................................................................ 12
3.4.1
Description ................................................................................. 12
4.
Options.............................................................................................................. 14
4.1 Simplex Changeover
Relay ..................................................................... 14
4.1.1
Description ................................................................................. 14
4.1.2 Installation
................................................................................. 14
4.2 U29 Balanced and Isolated VF plus E&MError!Bookmark not defined.
5. Technical
Description ...................................................................................... 16
5.1 Exciter Section
........................................................................................ 16
5.2 Receiver
Section...................................................................................... 16
5.2.1 General Radio Management
...................................................... 17
5.2.2
TX Signal Processing ................................................................. 18
5.2.3
RX Signal Processing ................................................................. 18
5.2.4
RF Power Control...................................................................... 19
5.2.5
User Interface............................................................................. 19
5.3 Powe
r A
mplifier Module......................................................................... 19
6. MX920 Base Station Fault Finding Procedure
............................................. 21
6.1 MX920 Base Station
............................................................................... 21
6.1.1 Transmitter Section
.................................................................... 21
6.1.2 Receiver
Section......................................................................... 22
6.2 Microcontroller Section of
PCB .............................................................. 23

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© SPECTRA ENGINEERING 2003 Revision 1.1.4
MX920 Base Station & Repeater
Technical Manual
6.3.1 VCO 23
6.3.2 RX Front End 23
6.3.3 IF Section 23
6.4 Excit r 24
6.4.1 VCO 24
6.4.2 RF 24
6.5 Powe
r
24
6.3 Receiver
Section...................................................................................... 23
e
7. Alignment and
Testing.................................................................................... 27
7.1 Transceiver Setup, Calibration and
Alignment ....................................... 27
7.1.1 Setting the Model Number and Serial
Number........................... 27
7.1.2 Setting the Configuration
Information ....................................... 27
7.1.3 Adding and Setting Channel
Alignments .................................... 27
7.1.4 Setting
CTCSS/DCS.................................................................... 28
7.1.5 Power
Calibration ...................................................................... 28
7.1.6 RSSI Calibration
........................................................................ 28
7.1.7 Temperature
Calibration............................................................ 29
7.1.8 TX Power
Adjustment ................................................................. 29
7.1.9 Peak Deviation and Modulation Balance
Alignment .................29
7.1.10 TX Centre Frequency
Alignment ................................................ 30
7.1.11 Microphone Line Input Level (Nominal Deviation Or Peak
Deviation
Mode)........................................................................ 31
7.1.12 Mute Threshold Setting
.............................................................. 31
8. Appendices
....................................................................................................... 32
8.1 MX920 Interface Connections
................................................................ 32
8.1.1 CN6 Simplex
Relay ..................................................................... 33
8.1.2 CN7 TX
Output ........................................................................... 33
8.2 MX920 Test
Points.................................................................................. 34
8.3 Establishing RS232
Communications ..................................................... 35
8.3.1 Software Menu
System................................................................ 36
8.3.2 Interfacing Information .............................................................. 37
8.4 MX920
Specifications ............................................................................. 37
8.4.1 Operating Frequency Bands
...................................................... 37
8.4.2
General ....................................................................................... 38
8.4.3 Transmit
..................................................................................... 39
8.4.4 Receive
....................................................................................... 40
8.4.5 Ancillaries
.................................................................................. 40
8.5 MX920 Model Number Configuration
Guide ......................................... 41

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© SPECTRA ENGINEERING 2003 Revision 1.1.4
Technical Manual
Table of Contents
List of Tables
Table 1-1 LED Functions ................................................................................................ 4
Table 1-2 Rear Panel
Connections.................................................................................. 5
Table 2-1 Micro Controller
Jumper.............................................................................. 10
Table 5-1 Microprocessor Port
Parameters.................................................................. 17
Table 7-1 Peak Deviation Settings
................................................................................ 29
Table 7-2 Nominal
Deviation ........................................................................................ 31
Table 8-1 MX920 Interface
Connectors........................................................................ 32
Table 8-2 MX920 Accessory Socket
Pinout................................................................... 32
Table 8-3 MX920 Test
Points......................................................................................... 34
Table 8-4 Rs232 Pin configuration
................................................................................ 35
Table 8-5 General
Specifications .................................................................................. 38
Table 8-6 Transmit
Specifications ................................................................................. 39
Table 8-7 Receive
Specifications ................................................................................... 40
Table 8-8 Ancilary
Specifications.................................................................................. 40
Table 8-9 MX920 frequencies
bands .............................................................................. 41

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© SPECTRA ENGINEERING 2003 Revision 1.1.4
MX920 Base Station & Repeater
Technical Manual
List of Figures
Figure 1-1 MX920 Horizontal andVvertical types of Front Panel LEDs......................... 3
Figure 1-2 MX920 Rear Panel with Power Supply and Duplexer
fitted. ........................ 5
Figure 7-1 Under (increase
level) ................................................................................. 30
Figure 7-2 Over (decrease
level)................................................................................... 30
Figure 7-3 Correctly Aligned
Waveform ....................................................................... 30
Figure 8-1 RJ45 socket viewed from front of
MX920.................................................... 33
Figure 8-2 Front veiw of DB9 female connector and RJ45 Modular male
connector ... 36
Figure 8-3 RS232
Cable ................................................................................................. 36