2-Channel Headset User Station with A5F Connector


RTS' RM-325 is a two-channel intercom user station for the RTS-TW Intercom System.  It is designed for use with a headset, and it can be placed on a desktop, or rackmounted with optional rackmount hardware.


  • Talk Features
    There is a separate talk button with talk-on indicator for each channel.  Talk buttons feature dual-action, momentary/latching talk operation: a button may be pressed and held to talk, then released when finished, or the button may be tapped once to turn talk on and then tapped again to turn talk off.  Latching operation may be independently deactivated for each channel via an internal DIP switch.  The channel 1 and 2 talk buttons may also be independently disabled via internal DIP switches.  Additionally, there is a an external talk switch input (for footswitch etc.) for each channel via the Aux connector.
  • Listen Features and Headsets
    There is a separate listen volume control for each channel, and a listen volume control for the program input.  The RM- 325 accepts a stereo, dynamic-mic headset or a monaural, carbon-mic headset.  Default operation is set for stereo listen, with channel 1 assigned to left headphone, channel 2 to right headphone, and program input to both headphones.  Internal jumpers permit all signals to be combined for monaural listening.  Internal jumpers also permit the program audio to be assigned left or right when using a stereo headset.
  • Microphone and Microphone Switch Features
    The Dynamic-mic headset connector features a balanced, dynamic mic input, and a mic on/off switch input.  A remote mic on/off switch may also be connected via the Aux connector.  There is an internal mic-sensing circuit for the carbon-mic headset jack, which activates the mic circuit when the carbon mic is on.  An internal jumper can configure the carbon mic input exclusively for use as a mic on/off switch input (monaural headphone output is supported in either case).  The microphone audio is available as an unswitched (hot, or always on) unbalanced output at the Aux connector.
  • Talk-off (Mic Kill) Signaling
    The RM-325 can send and receive Talk-off signals. Talk-off send and receive can be independently enabled/disabled via internal DIP switches.
  • Call Signaling
    There is a call button and indicator, and the RM-325 can send and receive call signals. There is also an internal setup switch to disable call send.
  • Program Input
    Balanced program audio may be input via the ¼-inch stereo phone jack (PGM) or via the AUX connector.
  • Line/Local Power Options
    By default, the RM-325 receives operating power from intercom channel 1. Alternatively it may be configured to receive power from channel 2 or from a local, 24 VDC power source connected to the AUX connector.
  • Sidetone
    There is a separate sidetone control for each intercom channel. These adjust the level of the station operator’s own voice in the headphones when talking.


  • Power Requirements, Channel Powered RM-325: 30 VDC nominal (standard TW line), 45 to 75 mA
  • Power Requirements, Locally Powered RM-325: 24 VDC nominal, 45 to 75 mA
  • Environmental Requirements:
    Storage: -40°C to 125°C; 0% to 95% humidity, non-condensing
    Operating: 0°C to 50°C; 0% to 95% humidity, non-condensing
  • Dimensions: 1.72" (44 mm) high, 8.2" (208 mm) wide, 8' (203 mm) deep
  • Weight: 2 lbs 12 oz (1.23 kg)
  • Noise Contribution: Less than -75 dB on the line
  • Common Mode Rejection Ratio: Greater than 40 dB from the line
  • Program Input:
    Maximum Input Level: 20 dBu
    Nominal Input Level: -10 to +8 dBu
    Frequency Response: 100 Hz to 12 kHz ±3 dB
  • Headphone Amplifier:
    Voltage Gain: 30 ±3 dB from the line
    Maximum Output: 150 mW into 50W
    Frequency Response: 100 Hz to 8 kHz ±3 dB nominal
    Output Voltage Level: 8 volts peak-to-peak
    Headphone Impedance: 50 to 600W
  • Sidetone: 20 dB minimum range, adjustable
  • Microphone Preamplifier: Maximum Voltage Gain: 54 dB
  • Frequency Response: 100 Hz to 8 kHz, nominal
  • Input Impedance: 1,000W, balanced
  • Limiter Range: 30 dB
  • Total Harmonic Distortion: Less than 0.2% nominal at Channel output


  • Auxiliary Connector
    Type: DB-15F
    Pin 1: Program input low
    Pin 2: Program input high
    Pin 3: Unswitched mic output high
    Pin 4: Foot switch in, channel 1
    Pin 5: Foot switch in, channel 2
    Pin 6: Local power (+24 VDC)
    Pin 7: Remote mic switch in
    Pin 8: Not Used
    Pin 9: Common
    Pin 10: Common
    Pin 11: Common
    Pin 12: Foot switch channel 1 common
    Pin 13: Foot switch channel 2 common
    Pin 14: Local power common
    Pin 15: Remote mic switch common
  • CARB MIC Headset Connector:
    Type: 1/4", 3-Conductor Phone Jack
    Tip: Microphone input high (or mic switch contact
    Ring: Headphone high
    Sleeve: Common
  • DYN-MIC Headset Connector:
    Type: XLR-6F 6-Pin Female Audio Connector
    Pin 1: Headset dynamic microphone low
    Pin 2: Headset dynamic microphone high
    Pin 3: Headphone and mic switch common
    Pin 4: Headphone left high
    Pin 5: Headphone right high
    Pin 6: Remote microphone switch contact
  • Intercom Line Input Connector:
    Type: XLR-3F 3-Pin Female Audio Connector
    Pin 1: Common
    Pin 2: Intercom channel 1 audio and power
    Pin 3: Intercom channel 2 audio
  • Intercom Line Loop Connector:
    Type: XLR-3M 3-Pin Male Audio Connector
    Pin 1: Common
    Pin 2: Intercom channel 1 audio and power
    Pin 3: Intercom channel 2 audio
  • Program Input Connector:
    Type: 1/4", 3-Conductor Phone Jack
    Tip: Program input high
    Ring: Program input low
    Sleeve: Common

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