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ID = 74990
United States of America (USA)
Brand: DeForest-Tubes
Developer: DeForest-Tubes 
Tube type:  Triode, vacuum   Audio Frequency 
Identical to audion_longanode

Base Edison (candelabra) 12 mm Other combinations of connections.
Was used by Telephony
Filament Direct / Battery =
Description This tube was designed at the de Forest laboratories but made for them by McCandless. It as to be a sample of a telephone repeater tube and was demonstrated by de Forest at the A. T. & T. company building at 463 West Street New York City on October 30th, 1912. this company was the manufacturing subsidiary of the Western Electric Company. The tube was a single element Audion but with an anode twice as long as the regular anode. (about 30 mm). From illustration 6.1 on page 85 of Tyne's "Saga of the Vacuum Tube", it appears that the filament was along inverted "V" with a possible anchor at the top. This seems to be embedded in the glass press used for the anode and grid leading-in wires. The filament voltage for this tube is not known. Western Electric retained the tube and did further experiments with it, leading to more efficient repeater tubes in the next few years. 
Dimensions (WHD)
incl. pins / tip
x 54 x mm / x 2.13 x inch
Information source Saga of the Vacuum Tube, Tyne   Pages 84 & 85

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