Majestic Ch= 70

Grigsby-Grunow (-Hinds) Co. (Majestic pre 1933); Chicago (IL)

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  • Year
  • 1928
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 43680

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

 Technical Specifications

  • Number of Tubes
  • 8
  • Main principle
  • TRF without regeneration; 3 AF stage(s); Neutrodyne
  • Tuned circuits
  • 4 AM circuit(s)
  • Wave bands
  • Broadcast only (MW).
  • Power type and voltage
  • Alternating Current supply (AC) / 90-130 Volt
  • Loudspeaker
  • Electro Magnetic Dynamic LS (moving-coil with field excitation coil)
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: Majestic Ch= 70 - Grigsby-Grunow -Hinds Co.
  • Shape
  • Chassis only or for «building in»
  • Notes

  • Push-pull af output stage; using the 7P6 or 7P3 power unit.

    This radio is a cascade of 3 individual TRF stages, each with its own feedback coil forming a Wheatstone bridge acting as a Hazeltine neutralization for the triode (described as the RFL circuit in contemporary sources). The feedback polarity is reversed with respect to the signal polarity through the Cag Miller-capacitance, in effect neutralising the triode tendency to oscillate.

  • External source of data
  • Ernst Erb
  • Circuit diagram reference
  • Rider's Perpetual, Volume 1 = 1931/1934 (for 1919-1931)

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