Majestic Ch= 70
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| Year: 1928 | Category: Broadcast Receiver - or past WW2 Tuner | ||||
| Valves / Tubes | 8: UX226 UX226 UX226 UY227 UX226 UX171A UX171A UX280 or CX380 | ||||
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| schematic requested | |||||
| 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 | |
| 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.
