75 Ch= 231 T

75 Ch= 231; Electrical Research (ID = 636445) Radio
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75 Ch= 231; Electrical Research (ID = 636445) Radio
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Country:  United States of America (USA)
Manufacturer / Brand:  Electrical Research Laboratories Inc. (Erla); Chicago, Illinois
Year: 1930 perfect model Category: Broadcast Receiver - or past WW2 Tuner
Valves / Tubes 7: 32 32 32 30 30 71A 71A
Main principle Special principle (see notes); Screengrid 1926-1935
Tuned circuits 4 AM circuit(s)
Wave bands Broadcast only (MW).
Power type and voltage Line / Batteries (any type) / 32 & 135 Volt
Loudspeaker Electro Magnetic Dynamic LS (moving-coil with field excitation coil)
Power out
from Model: 75 Ch= 231 [T] - Electrical Research
Shape Tablemodel, with any shape - general.

Farm radio, requires 32 V and an additional 135 V dry battery (or eliminator).
One dial (primary tuning control knob); 4-gang condenser; push-pull af output stage.
Dated 1929 since "Grinder" and "Radio Coll. Guide" say 1928, while schematic as well as the "Radio Set Socket Layout" show 1930.

According to Tyne, page 329, the tube UX230 (30) and the tube UX232 (32) arrived in 1930. Therefore this model can not be from before or had another first tube line-up.

Price in first year of sale 95.00 $
External source of data Ernst Erb
Source of data Radio Collector`s Guide 1921-1932
Circuit diagram reference Rider's Perpetual, Volume 2 = 1932 (Models 1931/1932)
Mentioned in The Radio Collector's Directory and Price Guide 1921 - 1965
Literature/Schematics (1) Radio Set Socket Layout 1921 to 1935, RCA

All listed radios etc. from Electrical Research Laboratories Inc. (Erla); Chicago, Illinois
Here you find 131 models, 45 with images and 61 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.