7AK7
{{Short description|Pentode vacuum tube}}
{{Infobox vacuum tube
|classification = Pentode
|service = Digital computers
|height_in = 3+5/32
|diameter_in = 1 +3/16
|weight_lbs =
|cathode_type = Coated Unipotential
|heater_voltage = 7.0 V (6.3 V nominal)
|heater_current = 800 mA
|max_dissipation = 8.5 W
|max_voltage = 200 V
|pinout = File:EIA-8VLO.svg
Pin 1 – Heater
Pin 2 – Anode (Plate)
Pin 3 – Grid 2 (Screen)
Pin 4 – Grid 3 (Suppressor)
Pin 5 – n.c.
Pin 6 – Grid 1 (Control)
Pin 7 – Cathode
Pin 8 – Heater
|reference = https://web.archive.org/web/20221114011216/http://www.nj7p.org/Tubes/PDFs/Frank/137-Sylvania/7AK7.pdf
}}
The 7AK7 is a pentode vacuum tube (thermionic valve). According to its manufacturer, Sylvania, it was "designed for service in electronic computers".Sylvania. [https://web.archive.org/web/20221114011216/http://www.nj7p.org/Tubes/PDFs/Frank/137-Sylvania/7AK7.pdf Engineering Data Service. 7AK7]. July 1953.
The tube was developed in 1948,{{cite book|first1=Tom|last1=Green|title=Bright Boys: The Making of Information Technology|publisher=CRC Press|year=2010|page=[https://archive.org/details/Bright_Boys_The_Making_of_Information_Technology_by_Tom_Green_2010/page/n150 141]|isbn=978-1568814766|url=https://archive.org/details/Bright_Boys_The_Making_of_Information_Technology_by_Tom_Green_2010}} designed at the request of L. D. Wilson for use in the Whirlwind computer.{{cite conference |first=L. D.|last=Wilson|title=Tube Reliability in the Univac|book-title=Proceedings of the National Electronics Conference|volume=10|publisher=National Engineering Conference, Incorporated|year=1954|article=746|pages=699–703}}
Significant attention was directed towards its manufacturing process in order to ensure the part's
David R. Brown, T. F. Clough, and P. Youtz. Investigation of 7AK7 Processing, Emporium, Pa., March 2, 1948.
URI: http://hdl.handle.net/1721.3/38986 Dubbed the "computer tube",{{cite book |last1=Haigh |first1=Thomas |first2=Mark |last2=Priestley |first3=Crispin |last3=Ropefir |title=ENIAC in Action: Making and Remaking the Modern Computer |year= 2016 |publisher=MIT Press |isbn=9780262334419 | page=211}} it became a popular tube for computers for a while. IBM, however, switched to more compact miniature tubes, starting with the IBM 604 in 1948.