RTS MRT-327 User Manual

MRT-327

User Station

The Model MRT-327 is a two-channel intercom station for use in RTS™ TW intercom systems. It may be used as a headset
station or as a speaker station (with an optional MCS-325 Modular Speaker). The MRT-327 may be installed in optional con­sole or rack mount configurations

Features

Call signaling

The MRT-327 can send and receive 20 kHz call signals.

Dual-Action Momentary/Latching Mic Switch

The Mic on/off switch can be used as a momentary push-to­talk switch or as a latching on/off switch.

Remote Deactivation

The MRT-327 can receive 24 kHz "talk-off” signals for deacti­vation of the MRT-327 microphone from a remote location.

Microphone Limiter

The microphone pre-amplifier circuit contains a limiter which
helps to equalize output for different voice levels.

Line Drawings

Optional Microphone Speaker & Headset Configurations

The standard MRT-327 accepts an unbalanced, dynamic-mic
headset or a dynamic microphone used in conjunction with an
external speaker located on the rear panel. It also has a jack
for an optional Model MCP-90-xx gooseneck panel micro­phone. Additionally, the MRT-327 may be internally modified
for use with a carbon or balanced-dynamic microphone. It can
also be modified to provide the microphone audio as an
unswitched, balanced output.

Powering Options

The MRT-327 receives operating power from the intercom
line. It may be internally modified for local powering from a
separate dc power supply or batteries.

MRT-327 Specifications

General

Input DC Voltage

ode: 18 to 35 volts DC

M

ocal Power: 15 to 35 volts DC (12 to 15 volts DC,

L

educed performance)

r

C Current Drawn from TW Line

D

Quiescent: 45 mA f10%
Operating, 25-ohm phones: 75 mA 210%
Operating, 25-ohm phones + call light: 90 mA f10%
Operating, 8-ohm speaker: 240 mA f108
Operating, %ohm speaker + call light: 300 mA 330%
Operating current is measured with output level at
10
Local power option draws no current from TW line.
DC Current Drawn from TW Line

Notes:

Operating current is measured with output level at
10 dB below clipping.
Local power option draws no current from TW line.

Impedance Across Line

10,000 ohms, minimum (designed for use with 200­ohm "W intercom lines)

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

(Ch 2): >-60 dBp
(Ch 1): >-80 dBp

Microphone Preamplifier

Input Impedance

470 ohms k 5% (dynamic mic)

Source Impedance

200 ohms, nominal

Maximum Input Level

150 millivolts

Frequency Response

(-54dB input): 100 HZ to 8 kHz S dB

Limiter Range

30 dB

Carbon Mic Excitation Current

10 mA, nominal

Current Source

Transfer Ratio

3.3 mA/volt = 3.3 milliseconds

Output

3.3 mA

into 200 ohms = fl volt peak, nominal

Speaker Amplifier

Maximum Voltage Gain

0 dB

3

requency Response

F

00Hz to8kHz*4dB

1

utput Power

O

1.5 watts into 8 ohms nominal
Speaker DIM (speaker muting during mic activation)
adjustable, -4 to -30 dB (Factory set to -6 dB)

Headphone Amplifier

Voltage Gain

34 dB

Output Voltage

8 volts peak-to-peak into 25 ohms nominal

Output power

1/2 watt peak into 25 ohms

Frequency Response

150 Hz to 10 kHz33 dB

Headphone Impedance Range

25 to 600 ohms (600 to 2000 ohms with reduced
levels)

Sidetone Adjustment Range

-20 dB to full on

Call Light

Signalling Frequency

'20 kHz +-100 Hz

Flashing Rate

5 Hz +-2 Hz

Talk-Off

Frequency

24 kHz nominal

Connectors

Dynamic Microphone Headset

XLR type 6pin female

Panel Microphone

1/4-inch standard phone jack, 3-circuit

Line Input

One (1) XLR type 3-pin female and one (1) XLR
type 3-pin male, wired in parallel

Mechanical

Dimensions

1.71" (44 mm) tall, 8.2" (208 mm) wide, x 9.0” (228

mm) deep
eight

W

2.75 lbs (1.25 kg)
Construction/Finish

Aluminum case, thermoplastic front panel, light gray
finish

Contact Information

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

Form Number: RTS-20153-3
August, 2005

Ordering Information

MRT-327 A5F

station • Catalog Number: 9000659300
MRT-327 A4F • 2 user programmable modular user
station • Catalog Number: 9000659301

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

• 2 user programmable modular user