Overview

The Telex MRT-327 is a 2-Channel User Station for use in RTS-TW intercom systems and A4F Headsets. It may be used as a headset station or as a speaker station. It can be installed in rack mount configurations.

Specifications

• Input DC Voltage:
• Mode: 18 to 35 volts DC
• Local Power: 15 to 35 volts DC (12 to 15 volts DC, reduced performance)
• DC Current Drawn from TW Line:
• Quiescent: 45 mA ±10%
• Operating, 25 ohm phones: 75 mA ±10
• Operating, 25 ohm phones + call light: 90 mA ±10%
• Operating, 8 ohm speaker: 240 mA ±10%
• Operating, 8 ohm speaker + call light: 300 mA ±10%
• 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 ohm, minimum (designed for use with 200O “TW” 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 ohm ±5% (dynamic mic)
• Source Impedance: 200 ohm, nominal
• Maximum Input Level: 150 millivolts
• Frequency Response: (-54dB input): 100 Hz to 8 kHz ±3dB
• Limiter Range: 30 dB
• Carbon Mic Excitation Current: 10 mA, nominal
• Current Source:
• Transfer Ratio: 3.3 mA/volt = 3.3 millisiemens
• Output: 3.3 mA into 200 ohm = ±1 volt peak, nominal
• Speaker Amplifier:
• Maximum Voltage Gain: 30 dB
• Frequency Response: 100Hz to 8kHz ±4dB
• Output Power: 1.5 watts into 8 ohm 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 ohm nominal
• Output power: 1/2 watt peak into 25 ohm
• Frequency Response: 150 Hz to 10 kHz ±3dB
• Headphone Impedance Range: 25 to 600 ohm (600 to 2000 ohm 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 6-pin female
• Panel Microphone: 1/4" 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
• Weight: 2.75 lbs (1.25 kg)
• Construction/Finish: Aluminum case, thermoplastic front panel, light gray finish