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Majestic Ch= 70

Majestic Ch= 70; Grigsby-Grunow - (ID = 676613) Radio
 
Majestic Ch= 70; Grigsby-Grunow - (ID = 676614) Radio
 
Majestic Ch= 70; Grigsby-Grunow - (ID = 676617) Radio
 
Majestic Ch= 70; Grigsby-Grunow - (ID = 676618) Radio
 
Majestic Ch= 70; Grigsby-Grunow - (ID = 676619) Radio
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Majestic Ch= 70; Grigsby-Grunow - (ID = 676613) Radio
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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
Valves / Tubes 8: UX226 UX226 UX226 UY227 UX226 UX171A UX171A UX280 or CX380
schematic requested
Main principle TRF without regeneration; 3 AF stage(s); Neutrodyne
Tuned circuits 4 AM circuit(s)
Wave bands Broadcast only (MW).
Details
Power type and voltage Alternating Current supply (AC) / 90-130 Volt
Loudspeaker Electro Magnetic Dynamic LS (moving-coil with field excitation coil)
Power out
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.



  
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