RTS CM300L User Manual

CM-300L

Console Mount User Station

The Model CM-300L is a console mount, two-channel intercom user station. The user station is designed to be used in a full
duplex, conference line intercom system.

Features

Volume Control

The volume control on the CM-300L has a wide range to com­pensate for: user hearing differences, ambient noise varia­tion, variations in headset / handset sensitivity, and variations
in voice. The volume control in the CM-300L reduces distor­tion by driving the headphone amplifier only as much as
needed.

Microphone Switch

In normal system operation, one or more users talk and the
others listen. A microphone switch on each station allows the
talker's microphone to be enabled and allows the listeners to
keep their microphones disabled. In this condition, speech
intelligibility is enhanced since background noise from other
microphones is not present. On the Model CM-300L, a toggle
switch turns the microphone on.

Line Drawings

The Channel Select Switch

A channel selector switch allows a choice of two (optionally
three) channels. When the switch is on the "1" position the
station talks and listens on channel 1, on the "2" position, to
channel 2.

Call Light Push Button

Pushing this button transmits a call signal to all other units on
the channel selected by the channel selector switch. A call
signal on this channel will cause the call light push button to
flash. The flash rate is 2 to 5 times a second. The call signal
itself is a 20 kilohertz signal.

CM-300L Specifications

Input DC Voltage

TW Mode: 18 to 35 volts DC
LP Option: 15 to 35 volts DC

attery: 12 to 35 volts DC (reduced performance)

B

DC Current Drawing from TW Line (Note: LP Option
draws no current from TW line)

Quiescent

CM-300/RM-300: 23 milliamperes ±10%
CM-300/RM-300L: 33 milliamperes ±10%

Operating 25 ohm headphones

CM-300/RM-300: 37 milliamperes ±10%
CM-300/RM-300L: 45 milliamperes ±10%

Operating 25 ohm headphones + Call Light

CM-300/RM-300: 60 milliamperes ±10%

Impedance Across Line: 10,000 ohms, minimum

Environmental

Temperature

Operating: 0°C to 60°C
Storage: -40°C to 85°C

Humidity

Operating and Storage: 5% to 95% non-condensing

Noise Contribution

One Unit: -75 dBu
Ten Units: -67 dBu

Microphone Preamplifier

Input Impedance: 470 ohms/dynamic mic
Source Impedance: 200 ohms, nominal
Maximum Input Level: 150 millivolts
Frequency Response: 100 hertz to 10 kilohertz ±3
dB (-54 dBu input)
Limiter Range: 30 dB
Carbon Mic Excitation Current: 10 millliamperes, nom­inal

Current Source

Transfer Ratio: 3.3 milliamperes/volt=3.3 millisiemens
Output: ±5 milliamperes into 200 ohms = ±1 volt peak,

ominal

n

Headphone Amplifier

Voltage Gain: 34 dB
Output Voltage: 8 volts peak-to-peak into 25 Ω
Output Power: 1/2 watt peak into 25 ohms
Frequency Response: 150 hertz to 8 kilohertz ±3dB
Headphone Impedance Range: 25 to 600 ohms (600
to 2000 with reduced levels)
Note: Do not use headphones with impedance less
than 25 ohms.
Sidetone Adjustment Range: -20dB to full on

Call-Light

Signaling Frequency: 20,000 hertz ±100 hertz
Flashing Rate: 5 hertz ±2 hertz

Auxiliary Connections

Headset Connector

Dynamic Microphone: XLR type 4-pin female
Carbon Microphone: 1/4” standard phone jack, 3-cir­cuit

Live Connection

Input: XLR type 3-pin female
Loop/External: XLR type 3-pin female

Mechanical (CM-300/CM-300L)

Dimensions: 2.75” (69.9mm) high, 6.25” (158.75
mm) wide, 6.4 (162.6mm) deep
Weight: 1.2 lbs (0.55kg)
Finish: Front Panel: Light Gray Enamel Paint,
Federal Standard 595A Color#26492
Chassis: Gold Iridite over aluminum

Contact Information

Telex® Communications, Inc.
12000 Portland Avenue South
Burnsville, MN 55337
Telephone: [phone]
Fax: [phone]

Form Number: 38110-492
August, 2005

Ordering Information

CM-300L A4F

with an A4F headset connector • Catalog Number:
9000264400
CM-300L A5F • 2 channel console mount user station
with an A5F headset connector • Catalog Number:
9000264403

This specifications information is preliminary and is subject to change without notification.
Brand names mentioned are the property of their respective companies.

• 2 channel console mount user station