Clear-Com MS-222 User Manual

DESCRIPTION
/ Clear-Corn
MS-222
2-Channel
Main Station
SECTION
1
O
DESCRIPTION
OF
THE MS-222
2-CHANNEL
INTERCOM
STATION
THE
CLEAR-COM
CONCEPT
Clear-Com
is a closed-circuit
intercom
system
that consistently
provides
high-clarity
communication
in high-noise
and low-noise
environments.
A basic
system
consists of
a
single-
or multi-channel
power
supply
or main station
connected
to various
single-
or
multi-channel
remote
stations,
such
as beltpacks
and
loudspeaker
stations.
Clear-Com
manufactures
a wide
variety of both
portable and
fixed-installation
units.
All
are compatible
with each
other. Clear-Corn
intercom
systems
can also
interface with
other communication
systems and
devices.
Clear-Com
stations are
interconnected
with two-conductor,
shielded microphone
cable,
using 3-pin
XLR connectors.
One
wire carries
the DC
power (28-30
volts) from
a main
station
or power supply
to all remote
stations,
and the other
wire carries
2-way
(duplex)
audio
information.
The shield acts
as a common
ground.
One termination
(per
channel)
is needed
throughout
the intercom
network, and
is usually
located in the
main station
or
power supply.
Clear-Com
is
a distributed
amplifier
system; each
main and
remote
station houses
its
own mic
preamplifier,
headset or
speaker power
amplifier,
and signaling
circuitry.
The
Automatic
Headset
Detection
circuit shuts
off a station's
mic pre-amp
when the
headset
is disconnected,
so background
noise on
the line is not
increased
by an unused
yet on-
line station.
Low-impedance
mic
input lines
(200 Ohms)
and specially
designed
circuitry
make
Clear-Com
channels
virtually
immune
to RFI
and
dimmer
noise.
Clear-Com
main
stations, power
supplies
and certain
remote stations
each
have an
auxiliary
program
input
with its own
volume
control,
which allows
an external
audio
source to
be fed to
the intercom
system.
Visual
Signal Circuitry
(CALL
Lights),
a standard feature
on most
main and
remote
stations, allows
the user
to attract
the attention
of operators
who have
removed their
headsets.
Depending
upon the
type of main
and remote
stations
selected and
assuming
that
enough
DC power
is available,
a maximum
number
of remote
stations from
1 0 (all
speaker stations)
to 30
(all headset
stations) can
be distributed
along
a mile of wire.
Remote
stations bridge
the intercom
line at
a very high
impedance
(>1 0 KOhms),
and
place
a minimum
load on
the line. The
audio level
always remains
constant,
and does
not fluctuate
as stations
leave and join
the network.
The 28-30
volts DC
provided
by main stations
and power
supply
units enable
remote
stations
to operate
with minimal
current
(25 mA. quiescent
for
headset stations,
50 mA.
quiescent
for
speaker stations)
while generating
extremely
loud
listen volumes
(greater
than 110dB
SPL using
Clear-Com
Headsets).
The higher
voltage and
low current
keep
voltage losses
to an absolute
minimum
in long
lines. If the supply
voltage
drops due
to
the addition
of great
length of
cable or many
more stations,
Clear-Com
equipment
will
continue
operating
with
less than
12 volts
available.
2/92 Rev.
1.1
Page
4

Clear-Com MS-222 Specifications

General

Brand	Clear-Com
Model	MS-222
Category	Intercom System
Language	English