Spectra Engineering MX950 Series User manual

DMR Repeater
SPECTRA
ENGINEERING PTY LTD
Technical Manual
MX950

Technical Manual MX950 Base Station & Repeater
© SPECTRA ENGINEERING 2022 Revision 1.0.0
i
Spectra Engineering Pty Ltd
ABN 65 057 696 438
731 Marshall Road
Malaga
Western Australia 6090
Tel: [phone] Fax: [phone]
Email: [e-mail]
Web: www.spectraeng.com.au
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 manufacturing and
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 2022
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.

MX950 Base Station & Repeater Technical Manual
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Regulatory Information
FCC COMPLIANCE
This device complies with part 15 of the FCC Rules.
Operation is subject to the following two conditions:
(1) This device may not cause harmful interference, and
(2) This device must accept any interference received, including interference that may
cause undesired operation.
FCC Interference Warning
Note: 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. Harmful interference is any emission, radiation or induction that endangers
the functioning of a radio navigation service or of other safety services or seriously degrades,
obstructs or repeatedly interrupts a radio communications service operating in accordance
CFR Title 47 Part 15.
HUMAN EXPOSURE TO RADIO FREQUENCY RADIATION (FCC)
USA Customers
Warning to comply with the maximum permissible exposure (MPE) limits referenced in 47
CFR 1.1310 , the following minimum safe operating distances must be observed:
MODEL
FREQ. RANGE
OPERATION
SAFE OPERATING
DISTANCES
MX950N5H
406.1 to 470 MHz
1.84 m*
Canada Customers
The MX950 radio transmitter has been approved by Innovation, Science and Economic
Development Canada to operate with the maximum permissible exposure (MPE) limits
defined in Radio Communication Apparatus (All Frequency Bands) , RSS-102, Issue 5, March
2015. The following minimum safe operating distances must be observed:
MODEL
FREQ. RANGE
OPERATION
SAFE OPERATING
DISTANCES
MX950N5H
406.1 to 470 MHz
2.36 m*
* The transmitter antenna(s) must be fixed-mounted on outdoor permanent structures.
Calculations based on folded dipole typ. gain 3.6dBi
INDUSTRY CANADA COMPLIANCE (ISED)
This device complies with Industry Canada license-exempt RSS standard(s). Operation is
subject to the following two conditions: (1) this device may not cause interference, and (2)
this device must accept any interference, including interference that may cause undesired
operation of the device.
FRENCH:
Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio
exempts de licence. L'exploitation est autorisée aux deux conditions suivantes : (1) l'appareil
ne doit pas produire de brouillage, et (2) l'utilisateur de l'appareil doit accepter tout
brouillage radioélectrique subi, même si le brouillage est susceptible d'en compromettre le
fonctionnement.

Technical Manual MX950 Base Station & Repeater
© SPECTRA ENGINEERING 2022 Revision 1.0.0
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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
June 2022
1.0.0
All - Initial Release
All

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SAFETY SUMMARY
Only the MX950 self contained power supply, if installed, contains dangerous mains
voltages within. Normal operation and use of the MX950 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 transmitting or operating the transmitter.
DO NOT SUBSTITUTE PARTS OR MODIFY THE EQUIPMENT
Because of the danger of introducing additional hazards, do not install substitute or lower
voltage parts to the equipment. Return to your authorised distributor.
Any modifications you make to this equipment which are not authorized by Spectra Eng.
may invalidate your compliance authority’s approval to operate the equipment.
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 MX950.
WARRANTY CONDITIONS & PRECAUTIONS
The following conditions are not covered by the warranty of the MX950. Please ensure that
the MX950 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 MX950 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.

Technical Manual Table of Contents
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Table of Contents
1. General Description........................................................................................... 1
1.1 Physical Description.................................................................................. 2
1.1.1 Front Panel .................................................................................. 3
1.2 Module Functional Description................................................................. 7
1.2.1 RF Module and Main Controller Assembly ................................. 7
1.2.2 Power Amplifier Module.............................................................. 8
2. Installation and Operation................................................................................ 9
2.1 Installation................................................................................................. 9
2.2 Screw Head Types................................................................................... 10
2.3 Operation................................................................................................. 11
2.3.1 Setting to Work........................................................................... 11
2.3.2 Adjustments ................................................................................ 12
3. Options.............................................................................................................. 13
4. Alignment and Testing.................................................................................... 14
4.1 Transceiver Setup, Calibration and Alignment ....................................... 14
4.1.1 Setting the Model Number and Serial Number .......................... 14
4.1.2 Setting the Configuration Information....................................... 14
4.1.3 Adding and Setting Channel Alignments.................................... 14
4.1.4 Setting CTCSS/DCS.................................................................... 15
4.1.5 Power Calibration...................................................................... 15
4.1.6 RSSI Calibration ........................................................................ 15
4.1.7 Temperature Calibration............................................................ 16
4.1.8 TX Power Adjustment................................................................. 16
4.1.9 Peak Deviation and Modulation Balance Alignment................. 16
4.1.10 TX Centre Frequency Alignment................................................ 17
4.1.11 Nominal Deviation ..................................................................... 18
4.1.12 Mute Threshold Setting .............................................................. 18
5. Appendices ....................................................................................................... 19
5.1 MX950 Interface Connections ................................................................ 19
5.2 Rear interface Board................................................................................ 19
5.2.1 Rear User Interface.................................................................... 19
5.2.2 CN4 Pinouts ............................................................................... 20
5.3 MX950 Specifications............................................................................. 21
5.3.1 Operating Frequency Bands ...................................................... 21
5.3.2 General....................................................................................... 22
5.3.3 Transmit ..................................................................................... 23
5.3.4 Receive ....................................................................................... 24
5.3.5 Ancillaries .................................................................................. 24
5.4 MX950 Model Number Configuration Guide......................................... 25

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Technical Manual Table of Contents
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List of Tables
Table 1-1 LED Functions................................................................................................ 4
Table 1-2 Rear Panel Connections.................................................................................. 6
Table 2-1 Micro Controller Jumper.............................................................................. 11
Table 4-1 Peak Deviation Settings ................................................................................ 16
Table 4-2 Nominal Deviation........................................................................................ 18
Table 5-1 MX950 Interface Connectors........................................................................ 19
Table 5-2 General Specifications.................................................................................. 22
Table 5-3 Transmit Specifications................................................................................. 23
Table 5-4 Receive Specifications................................................................................... 24
Table 5-5 Ancilary Specifications.................................................................................. 24
Table 5-6 MX950 frequencies bands.............................................................................. 25

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List of Figures
Figure 1-1 MX950 Front Horizontal View....................................................................... 3
Figure 1-2 MX950 Rear Panel........................................................................................ 6
Figure 4-1 Mod Under (increase level)......................................................................... 17
Figure 4-2 Mod Over (decrease level) .......................................................................... 17
Figure 4-3 Correctly Aligned Waveform....................................................................... 17

Technical Manual
© SPECTRA ENGINEERING 2003 Revision 1.1.4 1
1. General Description
The MX950 series equipment is a cost effective professional solution with full sub
band capability. Packaged in an compact hand portable carry case suitable for instant
deployment. DMR applications use 6.25e kHz TDMA Tier 2, conventional mode
Repeater. Operating modes can be software upgraded to cater for feature and system
release updates.
The MX950 series employs state of the art design and construction methods to deliver
a range of high performance, very reliable radio base stations and repeaters. They are
ideally suited for use in VHF or UHF two-way voice communications radio systems.
Fractional synthesizers’ and the two-point modulation method give the added
advantage of linear frequency and phase response from DC to 3 kHz for accurate
reproduction of voice and low frequency digital signalling systems. The Receiver and
Exciter circuits are contained in single special aluminium housing together with the
associated audio processing and digital control on a single circuit board. The Power
Amplifier is also contained in its own extruded aluminium housing and can be easily
removed from the main chassis. The MX950 also incorporates ‘Plug and Play’
technology and performs automatic self-calibration. A complete module changeover is
field replaceable in very short time.
The MX950 employs some unique features in its design and much thought and
consultation has been used to provide a product that offers an extreme degree of
flexibility for the installer and service person. For example, all options may be easily
field retrofitted at a later date. In addition, servicing is simplified with PCB's having
all components on one side of the PCB. This permits the Technician to diagnose
problems while either still connected in the chassis or powered simply and
independently on the test bench.
The flexibility of the MX950 series allows it to be configured for a wide range of
applications without removing any covers.
Standard MX950 applications include:
Analog Voice Repeater
DMR Repeater
The MX950 incorporates special technical features, of which the key ones are listed
below:
Extremely low conducted emissions
Extremely low transmitter spurious
Fast transmitter on time
Transmitter frequency response down to DC
Low group delay distortion
Full sub band RF switching bandwidth
No re-tune design for receiver and transmitter
Fully software programmable
Built in diagnostics

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CTCSS, Full duplex DCS, DMR Colour codes and many other options included
as standard
Programmable channel spacing
Flash upgradeable
In addition, the MX950 can be fitted with options, not being limited to the following:
Power supply
Duplexer
Batteries for power backup system.
Note: Not all options and features may be available at the time of order. Please also
refer to Spectra Engineering’s web site for software feature upgrades and additional
documentation as available. www.spectraeng.com.au
1.1 Physical Description
The MX950 series equipment is a cost effective professional solution with full sub
band capability. Packaged in an compact hand portable carry case suitable for instant
deployment. Its 296mm High, 228mm Deep, 174mm Wide and the weight is less than
5.4kg
The unit consists of four main sub assemblies, the main RF assembly, a Power
Amplifier Module, Logic controller and rear interface PCB's. These modules are
housed in sturdy aluminium and steel case.
The MX950 features a high degree of RFI and EMI screening throughout the design
and construction. The receiver and exciter RF circuits are contained in solid
aluminium enclosure. The PA module is contained in a special compact and efficient
extrusion for minimum harmonic radiation. This design results in low conducted and
radiated emissions and minimal susceptibility to RFI and EMI.
User interface is via the rear panel sockets which includes a DC power in , USB and
Ethernet ports for software programming and upgrading.

Technical Manual Installation and Operation
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1.1.1 Front Panel
1.1.1.1 Standard Front Panel
The MX950 front panel provides the user with real time status of the MX950.
Figure 1-1 MX950 Front Horizontal View
Mute / Squelch Adjustment
The squelch is used to eliminate any annoying background noise when
there are no signals present. This is pre-calibrated at the factory, to provide
the user with 5 useable settings. These can be set via the channel edit
menu.
When the Squelch is Open, the receiver's background noise can be heard
and ' RX A or B ' is lit on the front panel display. When the Squelch is
closed, the receiver remains quiet when there are no signals present but any
incoming signals will override the Squelch and will enable the TTR
function.
When CTCSS/DMR colour code is enabled the channel remains quiet until
someone transmits using the same tone/colour codes. When the
transmission ends, the channel becomes quiet again. By using different
tones\colour codes, several groups of people can share the same channel
without disturbing each other. DMR also extents this via talk groups.
NOTE: If an incoming signal is very weak and is close to the minimum
squelch level, it may become broken or “chopped” by the squelch action.
To prevent this, simply decrease the squelch to allow the signal to be heard
clearly. Alternatively, you can reduce the squelch sensitivity as described
above to block out unintentional weak signals.

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Table 1-1 below explains the functions of the front panel LED's. Each LED indicates
the status of the MX950 in real time.
LED
COLOR
FUNCTION
POWER
White
White only on initial power up and will
change to one of the colours below.
No display indicates the voltage is not
normal.
Blue
Current Channel programmed for DMR
mode
Green
Current Channel programmed for FM
mode.
YELLOW
Current Channel programmed for Mixed
mode. (DMR/FM)
RED
Indicates the power supply voltage is not
within limits.
RX
Blue
Analog Mode: A signal is being received by the
receiver or the receivers squelch is open.
Digital Mode: Inbound Slot 1 is receiving the
receivers squelch is open.
Green
Analog Mode: A signal is being received by the
receiver or the receivers squelch is open.
YELLOW
Digital Mode: Inbound Slot 2 is receiving the
receivers squelch is open.
Purple
Digital Mode: Inbound Slot 1 & 2 is receiving
the receivers squelch is open.
TX
BLUE
Digital Mode: Outbound Slot 1 is transmitting
DIGITAL
RED
Analog Mode: The transmitter is transmitting
RF power.
TX A
YELLOW
Digital Mode: Outbound Slot 2 is transmitting
TX B
Purple
Digital Mode: Outbound Slot 1 & 2 is
transmitting
ALARM
RED
A prearranged alarm condition exists.
ALARM: PA over temperature; or
ALARM: Low Power shut down; or
ALARM: Low power supply voltage; or
ALARM: High power supply voltage;
GOLD
ALARM: High reflected power); or
ALARM: Low forward power; or
ALARM: Tx VCO unlocked;
Blue
ALARM: Rx VCO unlocked; or
ALARM: PA calibration
Table 1-1 LED Functions

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1.1.1.2 Rear Panel
Conn Type
Function
Description
Mini-Fit Jr ,4P
DC Power input
13.8 Volt DC power input.
N TYPE
N type RX input
The input to the receiver for full duplex
operation.
N TYPE
TX output
The RF power output from the transmitter for
full duplex operation.
RJ45
Ethernet
Gives the base station an identity as a network
element, and provides the physical
connections for the Ethernet
USB
USB TYPE B
Serial Data interface.
Table 1-2 Rear Panel Connections
Figure 1-2 MX950 Rear Panel.
(RF Connecting cables not shown)

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1.2 Module Functional Description
1.2.1 RF Module and Main Controller Assembly
The MX950 consists of a full duplex RF module with its own shielded metal housing
and a Main Controller board integrated on a single PCB. Using advanced yet
simplified circuit designs, the size and complexity is reduced. This affords a number
of advantages including;
Cost reduction
Reduced number of components improves reliability and MTBF
Consistent and improved manufacture
Elimination of connectors and cabling
Reduction of human error
Faster maintenance or swap out
The Exciter module generates the low level, on frequency, RF transmitter signal
which is later amplified to nominal output power level by the Power Amplifier
module. The exciter consists of a Voltage Controlled Oscillator (VCO) and associated
main RF board, which, in conjunction with the reference oscillator and the PLL
circuitry, forms a two-point modulation programmable frequency synthesiser.
Frequency programming data is received from the Micro Controller via an 3 wire
serial data bus.
The exciter circuitry features a modulation bandwidth from DC for accurate CTCSS
and DCS generation and a wide RF switching bandwidth which covers the entire sub-
band. The average maximum RF output power is > +24.7 dBm / 300 mW. Normally
no adjustments are required, however should the carrier freq need re-alignment for
future maintenance, the TCXO reference oscillator frequency can be adjusted
manually or electronically adjusted via software settings.
The fractional N synthesiser provides ultra low spurii while still maintaining fast lock
times. The frequency step size is auto determined at 5.0 kHz or 6.25 kHz.
The receiver section accepts the low level RF input signal and amplifies, filters and
conditions the signal prior to detecting the wanted audio component. The Receiver
features the same advanced synthesiser and wide bandwidth as the exciter. The front
end bandpass filter uses very high tolerance components to minimise production
spread variations has a wide bandwidth and eliminates the need for future alignments.
The bandwidth is equal to the band allocation (refer to Section 5.4 for details of the
band allocations). The VCO has low phase noise and covers the full sub-band.
The receiver has high sensitivity while maintaining excellent Intermodulation
immunity and adjacent channel rejection. A dual first IF filter provides excellent
rejection to common known spurious responses. High blocking of over 100 dB typical
ensures that strong interfering signals do not desensitise the receiver when receiving
weak signals.
The Micro Controller section is physically located towards the centre on the main
board and controls all signal connections (apart from the RF connections). It controls
the operation of the RF sections and acts as the interface between the user controls,
indicators and the RF sub sections. Together with the VF DSP chip, processed

MX950 Base Station & Repeater Technical Manual
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transmit and received audio is passed to and from the Exciter and Receiver sections as
well as providing all other audio signalling functions of the transceiver.
An on onboard EEPROM stores all of the user channel related data such as
frequencies, CTCSS tones etc. A serial port at the Microphone accessory socket of the
MX950 provides access to the Controller card software configurations for the purpose
of the user to create and change this channel related information.
Special functions capable of being carried out include non-predictive full duplex
CTCSS encoding/decoding, DCS encoding/decoding, DMR Colour codes. Digipots
under the control of the processor ensure that user set up levels for TX deviation and
power levels are correctly set for each channel.
1.2.2 Power Amplifier Module
The PA receives the low level modulated RF signal from the Exciter RF output and
amplifies and filters it to final output power level. Forward and reflected power
voltages are fed to the Micro Controller.
The PA is very compact and efficient for high reliability and low cost. The heatsink
has minimal temperature rise even under continuous operation, ensuring the best
MTBF obtainable for a practical design. A low loss 13 element elliptical low pass
filter ensures that harmonics remain below –90 dBc. The new PA module uses the
latest LDMOS technology and using only two active RF transistors improves
efficiency and increases the operating bandwidth. At the same time this reduces the
number of components used and further improves the long term reliability.

Technical Manual Installation and Operation
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2. Installation and Operation
2.1 Installation
The MX950 Radio is securely packed for transport within a pasteboard container.
Before unpacking the MX950 radio, please inspect the packaging for signs of damage
and report any damage to your MX950 distributor.
Upon unpacking of the MX950 radio, please ensure that all items shipped were
received, report any missing items to your MX950 distributor.
Check the fan is free or does not look blocked as operation of the radio will be
affected if any packaging or shipping damage causes the fan to stop working.
If you intend to install the radio in an equipment rack consult the suppliers
instructions for your system. If the radio is to be used in a stand-alone configuration,
ensure that it is in a secure, dry location with sufficient air space around it to allow for
adequate ventilation. It is recommended that the chassis is earthed to the equipment
rack.
Equipment connection details are located in Appendix 5.1. The MX950 will draw
approximately 15 to 17A (band dependent) for 100 Watts, <10A for 50W model on
transmit and the gauge of the DC cable fitted to the 12V supply connector should be
adequate to ensure less than 0.5V volt drop at this current.

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2.2 Screw Head Types
Modern screws employ a wide variety of drive designs, each requiring a different kind
of tools to drive in or extract them. Spectra Engineering has chosen the Pozidriv ®
screw head and screwdriver as it preferred screw type on all of its products, sizes 1 &
2. This is because the Pozidriv system is the choice for high volume assembly
operations. It provides self-centring system and excellent driving control with less
operator fatigue.
It is similar to the classic Phillips cross-head. The differences lie in the way that the
heads are machined. The Phillips head has 4 simple slots cut out of it, whereas in the
case of the Pozidriv each slot is the result of two machining processes at right angles.
The result of this is that the arms of the cross are parallel sided in the case of Pozidriv,
and tapered in the case of Phillips. The Pozidriv has four additional points of contact,
and does not have the rounded corners that the Phillips screw drive has.
Phillips screwdrivers will usually work in Pozidriv screws, but Phillips screwdrivers
are likely to slip or tear out the screw head when used in Pozidriv screws. It is
important that you use the correct type and size screwdriver to avoid damaging the
screw head.
Exrta contact points Figure 1-1 Top view of screw heads
Pozidriv Philliips
Parallel sides Tapered sides
Figure 1-2 Side View of screw Heads
Exrta contact ridges
Parrallel driving flute
Tapered driving flute
Figure 1-3 Screw driver Tip View
Used on All
Spectra products Don’t used this type
on Spectra products
Pozidriv Phillips