Keyer TM-10

MILITARY U.S. (different makers for same model)

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  • Year
  • 1943 ?
  • Category
  • Audio Amplifier or -mixer
  • Radiomuseum.org ID
  • 360405

Click on the schematic thumbnail to request the schematic as a free document.

 Technical Specifications

  • Number of Tubes
  • 8
  • Wave bands
  • - without
  • Power type and voltage
  • Alternating Current supply (AC)
  • Loudspeaker
  • - For headphones or amp.
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: Keyer TM-10 - MILITARY U.S. different makers
  • Shape
  • Tablemodel, with any shape - general.
  • Notes

  • The TG-10 series of military keyers were automatic code practice devices designed for training signal personnel in Morse code transmission. These units generated 800 Hz audio signals from inked tape recordings or external keys, supporting large-scale group instruction with capacity for 300–1,000 headphones.

    Key Features

    • Dual Operation Modes:
      • Tape-driven mode: Played pre-recorded inked tapes (except TG-10-A) using a motorized transport system
      • External keying: Compatible with manual/automatic telegraph keys when tape mechanism inactive
    • Output: 800 Hz audio signal at sufficient power to drive:
      • Direct headphone connections
      • Practice tables (EE-94-B/EE-95-B/EE-96-B code training systems)
    • Recording Compatibility: Integrated guide/pressure rollers for ink recorders (all models except TG-10-A)

    Model Variations
    TG-10-(1) Series (A/B/C):

    • 25-cycle power transformers and motors (A model)
    • 60-cycle variants (B/C)
    • Single bias adjustment (40)

    TG-10-(2) Series (D/F/G/H/J):

    • 60-cycle operation with redesigned motor/drive assembly
    • Dual bias adjustments (26 + 40)
    • Added components:
      • Motor switch (43)
      • Additional guide roller (99(T))
      • Dial lamp1
    • Circuit modifications:
      • 4,000Ω resistor (39) replacing 4,700Ω (27-1)
      • 2,500Ω resistor (27) replacing 4,700Ω (27-2)
      • 200Ω resistor (40) added

    Specialized Variants:

    • TG-10-J: Included resistors 36-1/36-2 (250Ω each) for stabilized operation
    • TG-10-F: Optimized for group instruction with 300-headphone capacity

    Technical Specifications

    • Power Input:
      • 25-cycle AC (TG-10-A)
      • 60-cycle AC (all other models)
    • Output Voltage: Adjustable via bias controls (26/40)
    • Mechanical:
      • Differential speed indicator assembly (TG-10-(2))
      • Tape transport with dual pinch rollers

    Operational Notes

    • Models E and I were never produced
    • Concurrent tape/external key operation prohibited to prevent system damage
    • Required periodic resistor calibration for signal clarity
  • Mentioned in
  • - - Manufacturers Literature (War Department Technical Manual T M 11-447)
  • Author
  • Model page created by Gary Cowans. See "Data change" for further contributors.

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