Majestic 72 Louis XVI Ch= 70 - 7B Late

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

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  • Year
  • 1928/1929
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 43683

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

 Technical Specifications

  • Number of Tubes
  • 8
  • Main principle
  • Special principle (see notes); 3 AF stage(s)
  • 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
  • Wooden case
  • from Radiomuseum.org
  • Model: Majestic 72 Louis XVI Ch= 70 - 7B [Late] - Grigsby-Grunow -Hinds Co.
  • Shape
  • Console, Highboy (legs > 50 %).
  • Dimensions (WHD)
  • 25.5 x 52 x 17 inch / 648 x 1321 x 432 mm
  • Notes

  • One dial (primary tuning control knob) This set has a push-pull output stage using two 171A power tubes. It is made of walnut with burl walnut front panels and came with a Majestic electric power unit and Majestic dynamic power speaker.
    Model 72 uses the 7P6 or 7P3 (7BP6 or 7BP3 for chassis 70-B) 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.

  • Price in first year of sale
  • 167.50 $
  • External source of data
  • Ernst Erb
  • Circuit diagram reference
  • Rider's Perpetual, Volume 1 = 1931/1934 (for 1919-1931)
  • Literature/Schematics (1)
  • Grigsby-Grunow 1928 Flyer

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