COMTEK M-175 User Manual

M-175 OPERATOR’S MANUAL

M-175

Personal
Communication
Transmitter

357 West 2700 South • Salt Lake City, Utah 84115 • Phone: [phone] • Fax: [phone] • http://www.comtek.com

TABLE OF CONTENTS

Introduction ...........................................................

Setup ...............................................................................

Controls ..................................................................

Battery Removal / Replacement ......................................

Battery Charging ......................................................

Auxiliary Audio Input Operation ...................................

Snap-On Belt Clip .................................................

Frequency Selection ...............................................

Frequency Information ..........................................

P-7 Option ..............................................................

Optional Accessories ...............................................

Trouble Shooting .....................................................

Specifications .........................................................

Warranty and Service ..................................................

1

2

3

4

5

6-7

7

8

9-10

11

12

13-14

15

16

© 2012 COMTEK® All rights reserved.
Printed in the U.S.A. 01-16-12

INTRODUCTION

M-175

Personal
Communication
Transmitter

he M-175

T

personal
transmitter is a
professional
quality, compact
body-worn transmitter
designed for reliable one-way
remote communication. It’s ideal for many
applications including: personal cueing, assistive listening, tour guide
presentations, communication for on-the-job training, (requiring being
some distance away or in a noisy environment), and other personal,
one-way remote communication situations.

For a natural sound, this transmitter incorporates the latest digital and
analog technologies to produce high quality sound with low residual
noise, wide dynamic range and extended frequency response.

The audio processing circuit allows a choice of companded 2:1 audio
processing when used with Comtek full fidelity receivers, or
non-companded 1:1 audio processing on prescribed channels with
Comtek and other lower cost popular receivers. Both audio processing
systems have the same frequency response of 80 Hz to 10 KHz.
Operating under F.C.C. Regulation Part 90, the M-175 transmitter
has greater transmission range and reliability.

Page 1

M-175 SETUP

Setup

a. Check to ensure that the M-175 transmitter’s radio frequency channel is

the same as the associated COMTEK receiver’s channel. (Channels are
indicated by the rotary channel selector switches on the back of the
transmitter. See page 8.)

b. Open the battery door cover on the transmitter (see page 4) and
insert a new nine volt alkaline battery (Eveready E522 or equivalent). This
type of battery will offer up to 14 hours of operation. Replace the battery before

every use if the demand for fail-safe operation outweighs battery cost. The use of
carbon batteries is not recommended.

NOTE: If a rechargeable battery is to be used, ensure that it has been
allowed to charge at least twelve hours to bring it to full charge
(see page 5 for battery charger instructions).

c. Connect the microphone to the transmitter by inserting the microphone

plug into the receptacle on the top of the transmitter. The transmitter is
operating when the transmitter power switch is turned on and the battery
status/on indicator illuminates.

NOTE: The 48-inch microphone cord also functions as part of the
transmitter’s antenna system. For optimum performance, this cord
should be fully extended. Coiling or bunching the microphone
cord may reduce the range of the transmitter. The transmitter
should be carried by the snap-on belt clip (included) or in a pocket
or belt-clip pouch.

d. In a situation where an extremely loud voice or a very soft voice is used, it

is necessary to adjust the audio input gain control while observing the audio
“voice” level modulation indicator. A full bright LED indicates full audio
compression at 100% modulation. For best performance, the audio input
gain should be adjusted for some low level LED luminescence during
normal audio levels with occasional full bright peaks indicating 100%
modulation.

Page 2

M-175 CONTROLS

CHANNEL SWITCHES: These rotary switches are used to set

n

the transmitter to the desired operating frequency.
(See page 9 and 10 for frequency selection chart.)

BATTERY COMPARTMENT: The battery

o

compartment features a hinged battery cover and
an alignment system that ensures proper battery
polarity. Battery installation and removal is
facilitated by simply manipulating the bottom of
the battery.

AUXILIARY AUDIO INPUT JACK:

p

Allows transmitter to use line level,
earphone level, or fixed AUX as an audio
source.

AUDIO “VOICE” MODULATION

q

INDICATOR: This indicator is used in
making adjustment with the Audio Input
Gain Control.

MIC / ANTENNA JACK: This jack accepts an

r

electret type microphone having a 48” long cord with a
micro-mini 2.5 mm mono plug. The microphone cord
functions as part of the transmitter’s antenna system and
must be in place for auxiliary audio input operation. If
microphone function is not necessary, the optional
microphone switch should not be on for this operation.

POWER / BATTERY STATUS INDICATOR: This

s

LED indicator will illuminate continuously when the unit is
on indicating normal operation. When the battery voltage drops below 6 volts, the LED
will flash rapidly, indicating that a new battery is needed.

OPTIONAL MIC SWITCH: This switch turns off the microphone without turning off

t

the transmitter carrier.

AUDIO INPUT GAIN CONTROL: This is a microphone and AUX level input gain

u

control. This control is used with the “Voice” modulation indicator.

ON / OFF SWITCH: This switch turns the transmitter on and off.

v

Page 3

M-175 BATTERY REMOVAL / REPLACEMENT

Low Battery Indicator

The LED on the top of the transmitter
indicates the status of the battery as
well as indicating that the unit is turned
on. When the transmitter is turned on,
the LED illuminates. If the battery is low,
the green LED will blink rapidly to warn
you that the battery will soon be dead.
Replace a low battery immediately.

Battery indicator LED

Battery Removal / Replacement

Pull back battery door latch and allow battery

cover door to spring open. To remove battery,

simply manipulate the bottom of battery out of

the compartment and remove.

To insert battery, face battery
with negative terminal in line with
large hole in battery compartment,
press battery into compartment and close
battery door until it snaps shut. Note: It is not
possible to put battery in backwards.

Page 4