Lectrosonics M175 Operating Instructions And Troubleshooting Manual

M175

Belt Pack Transmitter

OPERATING INSTRUCTIONS

and trouble-shooting guide

LECTROSONICS, INC.

Rio Rancho, NM

INTRODUCTION

Thank you for selecting the M175 Wireless Microphone Transmitter. The M175
Series transmitters operate on high band frequencies from 150 MHz to 216 MHz. It
is offered in three different versions to meet your specific needs. This manual
covers all versions.

Only the M175 series transmitters are covered in this manual. Receivers are
covered in separate manuals. All versions of the M175 Series transmitters will
operate with any Lectrosonics high band VHF receiver. A frequency matched
transmitter/receiver combination makes up a “wireless system”.

If you are new to wireless microphones, you will discover a new freedom of move­ment and level of convenience. If you are an experienced wireless user, you will be
pleased with the versatility and superior performance of the M175 design.

TABLE OF CONTENTS

INTRODUCTION .................................................................................................. 2

GENERAL DESCRIPTION .................................................................................. 3

CONTROLS AND FUNCTIONS .......................................................................... 4

BATTERY INSTRUCTIONS ................................................................................. 5

OPERATING INSTRUCTIONS ............................................................................ 6

TROUBLESHOOTING ......................................................................................... 7

SPECIFICATIONS AND FEATURES ................................................................... 8

SERVICE AND REPAIR ....................................................................................... 9

RETURNING UNITS FOR REPAIR ..................................................................... 9

WARRANTY ......................................................................................... Back cover

M175 Series transmitters are FCC type accepted under the following Parts:

Part 90 (150-172 MHz), Part 74 (174-216 MHz)

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Belt Pack Transmitter

GENERAL DESCRIPTION

The M175 Series transmitter is offered in three versions. The standard model is the M175. The
M175-LS has an additional audio mute switch on the front panel, and the M175DC has a proprietary
Digital Code Squelch* circuit to eliminate squelching problems caused by interference.

The digital code system provides much more reliable control over the receiver audio output than a
conventional squelch can provide. The transmitter generates an 8-bit code at turn on, and another
code at turn off, to open and close the audio output on the receiver. The squelch on the receiver
cannot be opened by anything other than the specific code it is programmed to receive. This type of
squelch system is even more important when the receiver is connected into an automatic mixing
system.

The M175 transmitter uses the microphone cord for the antenna. This feature eliminates the need
for the “dangling wire” antenna found on many transmitters.

The M175 Series transmitters use a crystal controlled oscillator and temperature compensation
circuitry to ensure that the transmitter does not drift over time or with age.

To suppress audible noise, a “compandor” noise reduction circuit is used which is compatible with all
Lectrosonics 170 series, 175 series, and 185 series receivers. In addition, the input limiting circuit
will absorb 12 dB of overload without distortion. The audio circuitry is extremely quiet, with low
distortion for natural reproduction of either voice or music. The wide input adjustment range of M175
Series transmitters allows the use of virtually any microphone. The M175 can even be used with line
level inputs such as tape recorders or musical instruments.

The M175 Series transmitters operate from a replaceable standard 9 Volt alkaline battery. A preci­sion battery test circuit continuously monitors the battery voltage. A highly visible LED glows as long
as the battery voltage is high enough to operate the transmitter. A 9 Volt alkaline battery will provide
up to 15 hours of operation.

The electret microphone input jack provides 5 Volts DC positive bias for all Lectrosonics’ electret
microphones. Many other electret microphones may be adapted to the M175 Series by making
simple wiring changes in the microphone connector.

Rio Rancho, NM – USA

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