MLS MLSH041 Especificaciones descargar pdf (Pagina 6)

LBI-38421A

DESCRIPTION

The MLS II series mobile radio is a synthesized radio,

utilizing microcomputer technology to provide high

reliability, high quality and high performance in two-way,

FM mobile communications. The MLSH041 radio operates

in the 150.8-174 MHz frequency range and provides an RF

power output of 40 watts with an allowable channel

separation of 10 MHz transmit and 5 MHz receive. The

channel separation does not apply in repeater talk-around

applications because the transmitter and receiver frequencies

are the same. The small size of the MLS makes it ideal for

front mounting in conventional vehicles, with operating

controls and indicators located on the Control Panel. The

standard radio with Control Panel is equipped with the

following:

•

Microcomputer control

•

RF channel synthesizer

•

Up to 16 RF channels

•

LED channel display

•

Channel Guard (CTCSS or DCG)

•

Carrier Control Timer (CCT)

•

0.0005% (5 PPM) frequency stability

The radio circuitry consists of a System

Control/Frequency Synthesizer Board (A801), a

Transmitter/Receiver Board (A802) and a Front

Panel/Control Unit (A803 and A804).

The circuitry also consists of Control Indicator Panel

(A804), an internal speaker, an antenna jack, a connector for

the microphone, and a power supply cable (refer to Figure 1

- Mobile Layout Diagram).

No power supply is used since the highest supply

voltage required for the operation of the radio is provided by

the vehicle battery. The radio is designed for operation in a

12-volt, negative ground vehicular system or as an AC

power mobile.

Access to each circuit board is easily achieved by

removing four (4) screws in the rear of the top and bottom

cover then removing each cover. All tuning controls are also

accessible with the covers removed.

Access to the Control and Indicator circuitry can be

achieved by removing the four (4) screws securing the front

panel to the chassis.

TRANSMITTER

The transmitter circuit consists of a broadband, fixed

tuned driver module and a power amplifier.

The RF power output level is internally adjustable for

related power output. Once the level is set, a sensing control

circuit holds the power constant over the temperature and/or

voltage variations within specified limits.

RECEIVER

The dual conversion receive circuit consists of a front

end section and two mixer/IF sections operating at 82.2

MHz and 455 kHz. The receive circuit also contains a

squelch and an audio section. The audio section provides a

4-Watt audio output into a 4-ohm load (internal speaker).

FREQUENCY SYNTHESIZER

The synthesizer drives the transmit circuit exciter and

the receive circuit first mixer and consists of a synthesizer

chip, a prescaler, a reference oscillator and the voltage

controlled oscillators (VCOs). The synthesized frequency is

controlled by the personality EEPROM and applied to the

Transmitter/Receiver board.

An Electrically Erasable PROM (EEPROM), on the

System Control and Frequency Synthesizer Board (A801)

stores the binary data for the transmit and receive

frequencies, Channel Guard tones, digital codes, and CCT

timing periods. The EEPROM is field programmable and

each channel can be individually programmed or

reprogrammed for the desired transmit and receive

frequencies, CG tones, digital codes, or CCT timing.

CONTROL PANEL

The Control Panel consists of the front panel housing,

an internal speaker, and a plug-in module (A804) that

determines the number of channels (2 to 16) and mode of

operation (with or without scan). Refer to Maintenance

Manual LBI-38424, listed in the Table of Contents of this

publication. The panel is made of highly durable plastic

with rounded corners and recessed controls and indicators

for passenger safety requirements (refer to the OPERATION

section for a description of the Control and Indicator

functions).

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