Majestic Ch= 70
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Main principle |
TRF without regeneration; 3 AF stage(s); Neutrodyne
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Tuned circuits |
4 AM circuit(s) |
Wave bands |
Broadcast only (MW). |
Details |
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Power type and voltage |
Alternating Current supply (AC) / 90-130 Volt |
Loudspeaker |
Electro Magnetic Dynamic LS (moving-coil with field excitation coil) |
Power out |
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from Radiomuseum.org |
Model: Majestic Ch= 70 - Grigsby-Grunow -Hinds Co. |
Material |
Metal case |
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) |
Literature/Schematics (1) |
Beitman Radio Diagrams, Vol. 01, 1926-1938 |
All listed radios etc. from Grigsby-Grunow (-Hinds) Co. (Majestic pre 1933); Chicago (IL)
Here you find 200 models, 118 with images and 154 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.