• Country
• United States of America (USA)

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

• Year
• 1928/1929

• Category
• Broadcast Receiver - or past WW2 Tuner

• Radiomuseum.org ID
• 43681

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 or CX380

• Main principle
• TRF without regeneration; 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
• Wooden case

• from Radiomuseum.org
• Model: Majestic 71 Ch= 70-B [Late] - Grigsby-Grunow -Hinds Co.

• Shape
• Console, Lowboy (legs < 50 %).

• Notes

• Push-pull af output stage; using the 7BP6 or 7BP3 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 C_ag Miller-capacitance, in effect neutralising the triode tendency to oscillate.

  This is the late version of Majestic model 71 from 1929 and later. See also the early version from 1928 with quite a different housing and chassis version 7A. We have found a picture of this later version as a low boy but are not sure if there is also a high boy with chassis version 7B - and vice versa. The difference can be seen on the plate: There you find the chassis Majestic 7, model 70 in the version 7A. This set and the early version have a push-pull output stage using two 171 power tubes. The Majestic 71 is made of walnut with burl walnut front panels and came with a Majestic electric power unit and Majestic dynamic power speaker.

• Price in first year of sale
• 137.50 $

• External source of data
• Ernst Erb

• Circuit diagram reference
• Rider's Perpetual, Volume 1 = 1931/1934 (for 1919-1931)

• Literature/Schematics (1)
• Beitman Radio Diagrams, Vol. 01, 1926-1938 (Rider's Perpetual, Volume 2 = 1932 and before)

• Literature/Schematics (2)
• The Grigsby-Grunow Co. Folder "Electric Radios" for Majestic.

• Other Models

• Here you find 201 models, 122 with images and 156 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)