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Midgetape Chief 400
Portable tape cartridge audio recorder - this page is a stub

Midgetape Chief 400 is a portable transistorised audio tape cartridge recorder, introduced in 1958 by Mohawk Business Machines in New York (USA) as the successor to the Midgetape 300. Although initially intended as a dictation machine, it was also used in surveillance as it could easily be hidden on the body. This was further promoted by the availability of a wrist­watch microphone and a shoulder holster. It is known that these devices were used by the CIA.

The device measures 220 × 100 × 55 mm and weights 1.2 kg without batteries. It was supplied in a leather case that could be carried from the shoulder. For covert recordings it was usually carried in a special cloth shoulder holster, that could easily be hidden under the clothing.

Audio frequencies between 150 and 5,000 Hz are recorded onto a 6.35 mm wide double-sided magnetic tape with a Mylar base, at a speed of 4.76 cm/s. The maximum recording time was 45 minutes per side, far less than contemporary Protona wire recorders like the Minifon P-55.
  

The latter had a recording time of sevaral hours. Mohawk tape recorders can be seen as the American competitor of the contemporary German Minifon wire recorders that were also used by the CIA. Mohawk was earlier to migrate to magnetic tape than competitor Protona, but – like all tape recorders – missed the extended recording time.

Mohawk MIdgetape 400 in leather carrying case
Mohawk MIdgetape 400 - front view
Mohawk MIdgetape 400 - rear view
With open lid and tape cartridge installed
Tape cartridge removed from the recorder
Battery and amplifier comprtment
Microphone
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Mohawk MIdgetape 400 in leather carrying case
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Mohawk MIdgetape 400 - front view
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Mohawk MIdgetape 400 - rear view
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With open lid and tape cartridge installed
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Tape cartridge removed from the recorder
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Battery and amplifier comprtment
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Microphone

Specifications
  • Device
    Miniature audio recorder
  • Purpose
    Dictation, covert recording
  • Model
    Midgetape Chief 400
  • Manufacturer
    Mohawk Business Machines
  • Year
    1958
  • Predecessor
    Midgetape 300
  • Successor
    Midgetape Professional 500
  • Medium
    Tape, Dupont Mylar base
  • Width
    6.35 mm (1/4 in)
  • Speed
    4.76 cm/s (1 7/8 in/s)
  • Cartridge
    45 min/side
  • Input
    ≥ 1 mV, 2000Ω
  • Output
    10 mW into 2000Ω
  • Response
    150 - 5000 Hz
  • W&F
    < 0.7%
  • S/N
    42dB
  • Bias
    20 kHz
  • Transistors
    4
  • Dimensions
    220 x 100 x 55 mm
  • Weight
    1.2 kg
  • Price
    US$ 269.50 (1958)
Transistors
  • 1 x GT81
  • 1 x GT-82
  • 2 x 2N406
Accessories
  • Microphone
  • Earphone
Options
  • 401
    Leather carrying case
  • 402
    Internal Power Amplifier with built-in speaker
  • 403
    Mains power supply unit (for 110V AC only)
  • 404
    Transcribing Control [5]
  • 405
    Cowhide briefcase concealment (with hidden microphone)
  • 406
    Same as 405, but without hidden microphone
  • 407
    Telephone pick-up coil
  • 408
    Wristwatch microphone
  • 409
    Concealable lapel microphone
  • 410
    Throat microphone
  • 411
    Standard microphone/speaker with clip stand
  • 412
    Shoulder holster
  • 420
    Car battery converter (12V)
  • 421
    Stethoscope-style earphones
  • 422
    Combined speaker/microphone with PTT
  • RL-60
    Tape cartridge 2 x 30 min.
  • RL-90
    Tape cartridge 2 x 45 min.
  • T-12
    Motor battery (12-15 hours)
  • T-50
    Motor battery (50+ hours)
Documentation
  1. Midgetape pocket tape recorder - Instruction Manual
    Mohawk Business Machines Corp., undated.

  2. Midgetape 'Chief' (400) Supplementary Instructions
    Mohawk Business Machines Corp., undated.

  3. Midgetape 300/400, Circuit Diagram 1
    Howard W. Sams & Co., Inc. 1960.

  4. Mechanical Parts List with exploded view 1
    Howard W. Sams & Co., Inc. 1959.

  5. Midgetape Transcribing Control 1
    Mohawk Business Machines Corp., undated.

  6. Midgetape Chief (400) Leaflet

  7. Midgetape Chief (400) datasheet and pricelist 1
    25 November 1957.
  1. Obtained from Vintage Technics website [1].

References
  1. Vintage Electronics, Mohawk Midgetape 400
    Retrieved December 2022.
Further information
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Crypto Museum. Created: Thursday 09 June 2022. Last changed: Monday, 12 February 2024 - 15:33 CET.
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