• Country
• United States of America (USA)

• Manufacturer / Brand
• Grigsby-Grunow (-Hinds) Co. (Majestic pre 1933); Chicago (IL)

• 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.

• Number of Tubes
• 8

• Valves / Tubes
• UX226 UX226 UX226 UY227 UX226 UX171A UX171A UX280

• 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 C_ag 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.

• Other Models

• Here you find 201 models, 122 with images and 157 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Grigsby-Grunow (-Hinds) Co. (Majestic pre 1933); Chicago (IL)