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LBI-38848
SPECIFICATIONS*
GENERAL
Regulatory Approval
FCC (United States)
DOC (Canada)
Operating Voltage
Battery Drain
Receiver (13.8 Vdc)
Off
Squelched
Unsquelched
Transmitter (13.8 Vdc)
Channel Spacing
Frequency Stability
Temperature Range
Dimensions (H x W x D)
(Less Accessories)
Height
Width
Depth
Weight
Antenna Impedance
TRANSMITTER
Frequency Range
Output Power
Audio Sensitivity
Spurious and Harmonics
Audio Distortion
Modulation Limiting
FM Hum and Noise
Audio Frequency Response
Per EIA Standards
RECEIVER
Frequency Range
Acceptable Frequency Displacement
Sensitivity (12 dB SINAD)
Spurious Response
Adjacent Channel Selectivity
Intermodulation Distortion
Audio Frequency Response
Audio Output
Audio Distortion
*
These specifications are intended primarily for use by service personnel. Refer to the appropriate Specification Sheet
for complete specifications.
2
AXATR-311-A2
TR-311
13.8 Volts ±20%
0.01 Amperes (maximum)
0.75 Amperes (maximum)
2.0 Amperes (maximum at 10 Watts audio,
External Speaker)
11 Amperes (maximum at 25 Watts RF)
25 kHz (12.5 kHz NPSPAC)
±1.5 PPM (±0.00015%)
-30C to +60C (-22F to +140F)
5.3 cm (2.1 inches)
18.2 cm (7.2 inches)
24.0 cm (9.5 inches)
3.0 kg (6.6 pounds)
50 Ohms
806.0125-824.9875 MHz
25 Watts (Intermittent duty cycle; EIA 20%)
125 mVrms (typical)
<-16 dBm
5% maximum
+5 kHz maximum (4 kHz max 821.000 - 824.9875 and
866.000 - 869.9875 MHz)
-45 dB
Within +1, -3 dB of a 6 dB/octave pre-emphasis curve
from 300-3000 Hz
851.0125-869.9875 MHz
±2.5 kHz minimum
-113 dBm minimum
70 dB minimum
68 dB minimum at ±25.0 kHz
65 dB minimum
Within +2, -8dB of a 6 dB/octave de-emphasis curve
from 300 -2700 Hz
10 Watts (External Speaker); 4 Watts (Internal Speaker)
5% maximum at 1 kHz
GENERAL DESCRIPTION
The Dual Format MDX™ Mobile Radio is a synthesized,
wideband radio that uses integrated circuits and microcom-
puter technology to provide high performance trunked opera-
tion. This radio operates in the Enhanced Digital Access
Communications System (EDACS
®
), GE-MARC trunking en-
vironments and in conventional communications systems. The
radio provides 25 Watts of RF power output in the 806.0125-
824.9875 MHz and 851.0125-869.9875 MHz bands. The re-
ceiver operates in the 851.0125-869.9875 MHz band.
All radio functions are stored in a programmable Electri-
cally Erasable PROM (EEPROM). The radio is field pro-
grammable using an IBM compatible personal computer with
the following equipment:
•
Serial Programming Interface Module
TQ3370
•
Programming Cable (19B801417P10)
TQ3372
•
MDX Series Programming
Software (EDACS)
TQ3373
•
MDX Series Programming
Software (GE-MARC only)
TQ3346
With the interface equipment and software, the computer
can be used to program (or re-program) customer system
frequencies, Channel Guard tones and options. Selection of
options is done during radio initialization using the PC pro-
grammer.
The Dual Format MDX™ Mobile Radio assembly con-
tains the following circuit boards and assemblies:
•
Power Amplifier Board
19C851822G1
•
RF Board
19D902123G22
•
System Board
19D901891G2
•
Audio/Logic Board
19D903963G1
•
Audio Amplifier Board
19D904025G2
•
Front Cap Assembly
19D904151G1
Table 1 - Standard Tone Frequencies (Hz)
67.0
71.9
74.4
77.0
79.7
100.0
103.5
107.2
110.9
114.8
146.2
151.4
156.7
162.2
167.9
1.
Do not use 179.9 Hz or 118.8 Hz in areas served by 60 Hz power distribution systems (or 100.0 Hz or 151.4 Hz in areas supplied with 50Hz power). Hum
modulation of co-channel stations may "false" Channel Guard decoders.
2.
Do not use adjacent Channel Guard tone frequencies in systems employing multiple Channel Guard tones. Avoid same-areas co-channel use of adjacent
Channel Guard tones whenever possible. As stated in EIA Standard RS-220, there is a possibility of decoder falsing.
3.
To minimize receiver turn-on time delay, especially in system using Channel Guard repeaters or receiver voting, choose the highest usable Channel Guard
tone frequency. Do not use tones below 100 Hz when it is necessary to meet the receiver response time requirements of EIA Standard RS-220.
The circuit boards are all mounted on a main casting to
provide easy access for servicing. Interconnect plugs are used
to connect the boards to eliminate pinched wires and other
wiring problems.
RF BOARD
The RF Board includes the programmable frequency syn-
thesizer, transmitter exciter, receiver front end and IF circuitry.
Synthesizer
The synthesizer circuit generates all transmit and receive
RF frequencies. The synthesizer frequency is controlled by the
microprocessor located on the Audio/Logic Board. Frequency
stability is maintained by a temperature compensated reference
oscillator module. Transmit audio is processed on the
Audio/Logic Board and applied to the synthesizer to modulate
the VCO and TCXO. The buffered VCO output drives both the
transmitter exciter and the receiver mixer.
Transmitter
The transmitter consists of a fixed-tuned exciter module,
a PA module and a power control circuit. The PA module
provides RF output to drive the antenna. The power control
circuit controls the PA module to maintain a constant output
power across the band. The RF output level is internally adjust-
able for rated power. Thermistors in the control circuit protect
the PA from overheating by reducing the power output level.
Receiver
The dual conversion receiver circuit consists of a front end
section, 45.3 MHz first IF, a 455 kHz second IF, and FM
detector. All audio processing and squelch functions are ac-
complished on the Audio Board.
POWER AMPLIFIER BOARD
The PA board (19C851822G1) amplifies the RF board
output then connects it back to the RF board where it is coupled
through a PIN diode antenna switch, the low-pass filter and the
directional coupler to provide 25 watts power output at the
antenna connector.
82.5
85.4
88.5
91.5
94.8
118.8
123.0
127.3
131.8
136.5
173.8
179.9
186.2
192.8
203.5
97.4
141.3
210.7
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