Majestic 71 Ch= 70-B Late
|
|
||||
| Year: 1928/1929 | Category: Broadcast Receiver - or past WW2 Tuner | ||||
| Valves / Tubes | 8: 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). |
| 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 71 Ch= 70-B [Late] - Grigsby-Grunow -Hinds Co. |
| Material | Wooden case |
| 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 Cag 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. |
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.
