• Year
  • 1928
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 199205

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 Ch= 70 - 7A [Early] - Grigsby-Grunow -Hinds Co.
  • Shape
  • Console, Highboy (legs > 50 %).
  • 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 can use the 7P6 or 7P3 power unit. See also Majestic model 72 with chassis 7-B.

    This model here shows the loudspeaker below that radio chassis and the B shows the opposite. Maybe one could chose, maybe it is typical for the two versions - we don't know yet. On the speaker unit one can read: Majestic, Power Speaker, Model G1 Serial no. 300012 (not sure, hard to see), for use with model 71, 72, 80 (not sure). The chassis reads: Majestic 7, Electric Receiver Model 70 Serial no. 7A-, Grigsby-Grunow Company, Chicago USA. The cabinet reads: Majestic, Electric Receiver, Model 72, Grigsby-Grunow Company, Chicago USA. There is a hum control adjust for minimum hum in speaker.

    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
  • 210.25 $
  • External source of data
  • Carlos Vázquez-Hancock
  • Mentioned in
  • October 27, 1928 Radio Doings magazine advertisement page 30
  • Author
  • Model page created by Ernst Erb. See "Data change" for further contributors.

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