• Year
  • 1935 ?
  • Category
  • Audio Amplifier or -mixer
  • Radiomuseum.org ID
  • 214995
    • alternative name: Operadio Mfg,

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

 Technical Specifications

  • Number of Tubes
  • 4
  • Main principle
  • Audio-Amplification
  • Wave bands
  • - without
  • Power type and voltage
  • Alternating Current supply (AC) / 115 Volt
  • Loudspeaker
  • - For headphones or amp.
  • from Radiomuseum.org
  • Model: 660 Pre-Amplifier - Operadio Corp.; St. Charles IL
  • Circuit diagram reference
  • Rider's Perpetual, Volume 8 = 1937 and before
  • Mentioned in
  • Rider's Misc. Page 8-6

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