Clear-Com TWC-704 - Manual (Page 7)

T W C - 7 0 1 A N D T W C - 7 0 4 A D A P T O R S
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OPERATION
INTRODUCTION
Congratulations on choosing this Clear-Com product. Clear-Com was
established in 1968 and remains the market leader in providing intercom
s for
entertainment, broadcast and industrial applications. The ruggedness and high
build-quality of Clear-Com products defines the industry standard. In fact, many
of our original beltpacks and main stations are still in daily use around the world.
We recommend that you read through this manual completely to better
understand the functions of the TW-701 and TW-704 adaptors. If you
encounter a situation or have a question that this manual does not address,
contact your dealer or call Clear-Com directly at the factory. Our applications
support and service people are standing by to assist you. (Refer to Chapter 3:
“Warranty” for contact information.) Thank you for selecting Clear-Com for
your communications needs.
STANDARD CLEAR-COM SYSTEM WIRING
Clear-Com stations normally interconnect with “standard” 3-pin XLR
microphone cable (two conductor shielded audio cable). This single cable
provides a single channel of full duplex, two way intercom, “call” signaling, and
the required DC operating power.
Multiple channel systems normally use separately shielded cables for individual
channels. This “single” cable or “pair per channel” system enables ease and
flexibility of station/channel assignments, simple power supply redundancy, and
a minimization of crosstalk between channels.
On standard cabling, one conductor (pin #2) carries power to the remote
stations. The second conductor (pin#3) carries full duplex, two-way intercom
audio and “call” signaling. The shield or drain wire (pin#1) is a common ground
for the power and the intercom audio/signaling.
The intercom line (pin#3) has a 200Ω impedance established by a passive
termination network (one network per channel). This termination is usually
located at the system main station or power supply.
All Clear-Com stations bridge the intercom line with a load impedance of 15Ω
or greater. This results in the audio level remaining constant, without
fluctuations as stations join or leave the channel.
Normally Clear-Com portable two channel intercom stations (usually beltpacks)
are connected with special 2- or 3-pair cables terminated with 6-pin XLR type
connectors. However, in some applications, it is desirable to access two discrete
channels over a single standard 3-pin microphone cable. The TWC-701 and
TWC-704 adaptors combined with intercom stations equipped with the “TW”
option makes two channel operation on a single 3-pin cable possible.
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