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7AK7

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ID = 5126
       
 
   
Tube type:  Vacuum Pentode 
Identical to 7AK7
First year 1948 en.wikipedia.org/wiki/Vacuum_tube
First Source (s)
20.Mar.1948 : Tube Lore
20.Mar.1948 : Electron Tube Registration List
Successor Tubes TE-40   6888  

Base Loctal-8, B8G (Sylvania, 1938)
Was used by Technology / Measurement
Filament Vf 6.3 Volts / If 0.8 Ampere / Indirect / Parallel, (AC/DC)
Description

From Wikipedia: "To meet the reliability requirements of the early digital computer Whirlwind, it was necessary to build special "computer vacuum tubes" with extended cathode life. The problem of short lifetime was traced to evaporation of silicon, used in the tungsten alloy to make the heater wire easier to draw. Elimination of the silicon from the heater wire alloy (and paying extra for more frequent replacement of the wire drawing dies) allowed production of tubes that were reliable enough for the Whirlwind project. The tubes developed for Whirlwind later found their way into the giant SAGE air-defense computer system. High-purity nickel tubing and cathode coatings free of materials that can poison emission (such as silicates and aluminium) also contribute to long cathode life. The first such "computer tube" was Sylvania's 7AK7 of 1948. By the late 1950s it was routine for special-quality small-signal tubes to last for hundreds of thousands of hours, if operated conservatively. This reliability made mid-cable amplifiers in submarine cables possible."

 
Tube prices 2 Tube prices (visible for members only)
Literature Essential Characteristics, GE 1973   
  7ak7.png
  7AK7: Internet
Miguel Angel Trujillo-Rodriguez
 
7ak7.jpg
7AK7
Danko Tkalec

 
7ak7_so.png
7AK7: ARRL Handbook 1972
Michael Schlör

 
7ak7_data.png
7AK7: Raytheon Manual
Heinz Höger



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