COMTEK BST-75 User Manual

BST -75 OPERATOR’S MANUAL (72-76 MHz)

Synthesized
Base Station
Transmitter

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

TABLE OF CONTENTS

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

Equipment Placement ...............................................

Power Requirements .......................................................

Remote Antenna ......................................................

Screw-in Whip Antenna ............................................

Audio Input Connections ...............................................

Audio Adjustments ...............................................

Audio Processing Circuit ..........................................

Front and Rear Panel Facilities ........................................

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

Accessories ..........................................................

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

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

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2
2
3
3
4
4
5
6-7
8-9
10-11
12
13

© 2011 COMTEK® All rights reserved
Printed in U.S.A. 01-18-11

INTRODUCTION

BST-75

Synthesized
Base Station
Transmitter

he BST -75 mini base station transmitter meets the highest

T

professional standards while offering outstanding value
and the most advanced technology available. This versatile and
innovative transmitter is simple to use, yet it has sophisticated
features such as “Flash Memory” 98-channel programmability
with synthesized manual 10-channel selectable user-switch. Plus
a unique multi-function R.F . indicator detects bad antenna load, RF
presence, coaxial cable short or open condition for quick and easy
trouble-shooting.

The compact design of this transmitter is ideal for multiple transmitter
installations. Up to four transmitters can be installed in one rack
space. Also, it operates in the 72-76 MHz band under FCC Regulation
Part 90. This allows a greater RF power capability (120 mW) for greater
range and reliability than customary FCC Part 15 systems.

The audio processing circuit produces full fidelity frequency response
from 80 Hz to 10 kHz with very low residual F.M. noise and distortion.
T o accommodate a greater variety of receivers, the BST -75 can operate
with non-companded receivers or with companded receivers for higher
fidelity sound reproduction with a signal-to-noise ratio of up to 100 dB.

All this is designed into a stylish, compact, all-metal enclosure suitable
for permanent rack-mount installations or can be battery powered for
stand-alone portable applications.

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OPERATING INSTRUCTIONS

Equipment Placement

If the BST-75 base station is to be rack mounted, a r emote antenna must
be used. The base station should be mounted away from equipment
that uses large power transformers to reduce 60 Hz hum possibilities.

Special Note: When using the base station in close proximity to other
audio equipment, ensure that the audio equipment is not susceptible to
RF interference. This can be accomplished by temporarily installing
the base station as per above, and then while the base station is
operating, checking all audio outputs for uncharacteristic noise. If a
problem is found, move the base station or the remote antenna as far as
possible from the affected equipment. Should you continue to have
problems, contact COMTEK’s Technical Support Services for
ass istance.

Power Requirements

The BST-75 base station is designed to be power ed by 12 volts AC
through a standard barrel type power jack (5.5mm X 2.1mm). The
AC power adaptor supplied (AP-12V AC) is used for permanent
installations and mobile applications
where AC power is available.
For field operation only , the
BST-75 base station will accept
12V DC through the power jack
with either positive or negative
12V to the center pin of the jack.
The on/off switch on the front
panel of the base station
transmitter should be
turned to the “off”
position when the power
plug is initially plugged
into the transmitter .

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OPERATING INSTRUCTIONS

Remote Antenna

When the BST-75 base station transmitter
is to be rack mounted for permanent
installation, a remote antenna must
be used. The RDA-2B remote dipole
antenna (or equivalent) or the COMTEK
“Phase Right Antenna” PRA-L72 high
performance omni antenna should be
used. These antennas must be placed
vertically polarized up to twenty feet
away from the transmitter with the
coaxial cable supplied. The highest
possible antenna placement away from
any metallic object is best. For high gain
directional yagi type antennas and
specialty antennas, contact COMTEK’s
Technical Support Services.

Integral Screw-in Whip Antenna

If the BST-75 base station transmitter is to be
used outside of the traditional rack-mounted
environment for stand-alone mobile type
applications, the screw-in whip antenna
(TWA-75) should be used. The transmitter
should be placed on a table or platform as
high as possible so the fully extended
whip antenna is at least 24” away from
any metallic object. The radiated output
power of the transmitter with this whip
antenna will not be as great as the remote
antennas. The BST-75 transmitter should
only be used in the high power setting when
the telescoping whip antenna is used.

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