Introduction, Radio Description, Options

LBI-38653

	SPECIFICATIONS (Cont.)
Spurious Emissions
Radiated	Meets FCC requirements
Conducted	-57 dBm maximum
RX Spurious Response	70 dB minimum
Adj Ch(2-Sig) Selectivity	-70 dB max @ 25 kHz (EIA)
Intermodulation Attenuation	-70 dB minimum
RX Modulation Acceptance	±7 kHz minimum
Audio Distortion	2% maximum @ 0.5 Watt (EIA)
	10% maximum @ 4 Watts and 1 kHz
Audio Frequency Response	Within +2, -8 or a 6 dB/octave de-emphases,
	300-3000 Hz (EIA)
RX Hum and Noise
Unsquelched	-45 dB maximum
Squelched	-70 dB maximum
Audio Output Power	4 watts, @ < 10% Distortion
Speaker Impedance	4 ohms
	MDS RADIO PACKAGE NUMBERS
	MDS RADIO PACKAGE NUMBERS
PACKAGE NUMBER	DESCRIPTION
TLU22	UHF MID-SPLIT 2 CHANNEL, 40 WATT
TLU28	UHF MID-SPLIT 8 CHANNEL, 40 WATT
TLU32	UHF HI-SPLIT 2 CHANNEL, 40 WATT
TLU38	UHF HI-SPLIT 8 CHANNEL, 40 WATT
	OPTIONS
OPTION NUMBER	DESCRIPTION
MC3G	DESK TOP MIC
AN1R	1/4 WAVE, ROOF MT ANTENNA W/TNC CONNECTOR
ZM3L	EXTERNAL WEATHERPROOF SPEAKER AND CABLE
LS1F	MIL SPEC SPEAKER, 4 OHMS, 5 x 5
CD1E	SPEAKER CABLE
PD1A	NOISE FILTER KIT
SU1C	ALARM RELAY KIT
EC1A	DOC POWER SET
MA1L	DESK TOP RADIO MOUNTING WEDGE
PS1D	240 VAC-12 VDC, 13A 50/60 Hz Power Supply
PS5K	120 VAC-12 VDC, 13A 50/60 Hz Power Supply

INTRODUCTION

The Ericsson GE Conventional MDS Radio is a rugged two-way FM mobile radio which operates in the 440-470 MHz and 470-512 MHz frequency bands. The MDS is a wide band synthesized radio utilizing microcomputer technology to provide reliable high quality simplex two-way mobile commu- nications. Its transmitter output power level is 40 watts over the wide bandwidth of each split. The receiver has an allow- able 12 MHz maximum receive channel separation. There are two versions available for each split, a 2-channel and an 8- channel. The basic radio package includes the following fea- tures:

∙Microprocessor Control

∙Synthesized RF Channel selection (frequency control)

∙7-Segment LED Channel Display

∙Multi-tone Channel Guard (CTCSS) Encode/Decode

∙Multi-code Digital Channel Guard (DCG) Encode/De- code

∙Automatic Hook Switch Channel guard Disable

∙Channel Activity Sensing (CAS)

∙Carrier Control Timer (CCT)

∙±5 ppm frequency stability

∙Talkaround, radio to radio direct Communication

∙Type 99 Tone Decode

∙Field Programmable with PC

∙Fixed Squelch, threshold programmable

∙Internal 4-watt Speaker, with volume control

∙Front Mounted Microphone Connector

∙Rear Mounted Antenna TNC Connector

∙Rear entry power connections

∙ANI Encode

The small size of the MDS radio makes it ideal for front mounting in conventional vehicles. The radio is operated with a simple hand held microphone in combination with the following operating controls, all located on the front panel.

∙Power ON/OFF Switch

∙Channel UP/DOWN Selector

∙Volume UP/DOWN Control

∙Monitor Switch for Channel Guard Disable

∙Type 99 Tone RESET Switch, to reset the tone decoder.

Refer to the Operator’s Manual LBI-38651 for a complete description of the operating procedures.

RADIO DESCRIPTION

MAIN BOARD ASSEMBLY

A sturdy aluminum casting houses the Main Board Assem- bly (N29/85154001220 for the 440 -470 MHz band N29/85154001250 for the 470-512 MHz band). There is com- plete accessibility to the Main Board with the radio’s top and bottom covers removed. The Main Board contains the following circuits:

∙Microprocessor and associated Logic

∙Frequency Synthesizer

∙Transmitter Exciter

∙Receiver

∙Audio Processing (for both transmit and receive paths)

∙Tone and Squelch Processing (for both transmit and receive paths)

∙Voltage Regulators

Logic Circuitry

The radio’s logic circuitry includes the 80C535 microproc- essor with associated EPROM and Electrically Erasable PROM (EEPROM) memory and latch circuitry. The Microprocessor controls the functions of the transmitter, the receiver, the inputs from the operator and the outputs to the operator.

Synthesizer

A programmable Synthesizer generates both transmit and receive operating frequencies. It includes a synthesizer chip, a dual modulus counter, a temperature compensated reference oscillator (TCXO) and a voltage controlled oscillator (VCO); all part of an operating phase lock loop, with its requisite loop filter.

Transmitter

The radio transmitter includes the Synthesizer’s modulated VCO and the fixed tuned exciter amplifiers. The exciter ampli- fiers are wideband, covering both splits in the UHF band without retuning. The exciter output is fed to the Power Amplifier Board through a coax cable. The exciter provides 35 dB of gain to drive the Power Amplifier with 3 watts. The transmitter output level at the antenna connector is factory set for a rated output power of 40 watts. The power control circuit detects the power output of the Power Amplifier. Using the errorsignal, the power control circuit varies the DC supply voltage to the first stage of the exciter. This will hold the transmitter output level constant.