Pair of 6L6GC tubes:
Left: General Electric version from 1960s
Right: current manufacture from Svetlana Electron Devices, Russia

6L6 is the designator for a vacuum tube introduced by Radio Corporation of America in July 1936. Pair of different 6L6GC tubes - (l) General Electric version from 1960s (r) currently made version by Svetlana Electron Devices, Russia (photo by Eric Barbour) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Pair of different 6L6GC tubes - (l) General Electric version from 1960s (r) currently made version by Svetlana Electron Devices, Russia (photo by Eric Barbour) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ... RCA, formerly an initialism for the Radio Corporation of America, is now a trademark used by two companies for products descended from that common ancestor: Thomson Consumer Electronics, which manufactures RCA-branded televisions, DVD players, video cassette recorders, direct broadcast satellite decoders, camcorders, audio equipment, telephones, and related accessories; and... 1936 (MCMXXXVI) was a leap year starting on Wednesday (link will take you to calendar). ...

History

The 6L6 is a descendant of the "Harries Valve" developed by British engineer J. Owen Harries and marketed by the Hivac Co. Ltd. in 1935. Harries is believed to be the first engineer to discover the "critical distance" effect, which maximized the efficiency of a power tetrode by positioning its anode at a distance which is a specific multiple of the screen grid-cathode distance. This design also minimized interference of secondary emission electrons dislodged from the anode. A tetrode is a two-grid vacuum tube. ... Diagram of a zinc anode in a galvanic cell. ... A grid introduced into a thermionic valve or tube to greatly reduce the capacitance between two other parts of the electrode structure. ... Diagram of a copper cathode in a Daniells cell. ... Secondary emission is a phenomenon that occurs in electron tubes where electrons impact an electrode with sufficient energy to knock additional electrons from the surface of that electrode. ...

EMI engineers Cabot Bull and Sidney Rodda improved the Harries design with a pair of beam plates, connected to the cathode, which directed the electron streams into two narrow areas and also acted like a suppressor grid to absorb some secondary electrons. The beam design was also undertaken to avoid the patents which the giant Philips firm held on power pentodes in Europe. Because this overall design eliminated the "tetrode kink" in the lower parts of the tetrode's voltage-current characteristic curves (which sometimes caused tetrode amplifiers to become unstable), MOV marketed this tube family under the sobriquet "KT", meaning "kinkless tetrode". A grid used in a thermionic valve (also called vacuum tube) to suppress secondary emission. ... Philips HQ in Amsterdam Koninklijke Philips Electronics N.V. (Royal Philips Electronics N.V.), usually known as Philips, (Euronext: PHIA, NYSE: PHG) is one of the largest electronics companies in the world, founded and headquartered in the Netherlands. ... In electronics, a vacuum tube (American English) or (thermionic) valve (British English) is a device generally used to amplify a signal. ... Generally, an amplifier is any device that uses a small amount of energy to control a larger amount of energy. ...

Because MOV's engineers did not feel the kinkless tetrode could be successfully mass-produced, they licensed the design to RCA — which proved to be a poor business decision on MOV's part. RCA subsequently had enormous success with the 6L6. It replaced the use of power triodes in public-address amplifiers almost overnight. So many applications were found for the 6L6 that a complete list would be impossible to assemble. MOV introduced their version, KT66, a year later. Original M-OV version of the KT66; this is from late production KT66 is the designator for a vacuum tube introduced by Marconi-Osram Valve Co. ...

The 6L6 Pinout, metal versions had the shell connected to pin 1

RCA's first version had a metal-canister shell rather than glass — being one of the early octal base tubes, most of which were marketed as having metal shells. Later versions, including the 6L6G, 6L6GA, 6L6GB, 5881, 5932, 7027, and the final version 6L6GC had glass envelopes, which made radiation cooling of the anode easier. The voltage and power rating of the 6L6 series was gradually pushed upwards by adding features such as a micanol base, thicker plates, thicker grid wires, grid cooling fins, and special ultra-black plate coatings. The original metal version was rated for 19 watts dissipation, while the later 6L6GC is usually rated for 30 watts. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Octal base has two possible meanings: a type of vacuum tube socket the octal numeral system, or base 8. ... Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the objects temperature. ...

Variations

The list of variations of the 6L6 design would fill a fat textbook. Early variations included transmitting tubes such as the 807 (1937), the smaller 6V6 (1937), the many KT versions marketed in Europe, and a subsequent vast array of audio and RF power tubes. One of the largest post-WWII applications was in the basic design of television sweep power tubes, starting with the 6BG6 (1946), a modified 807. TV sweep tubes were not replaced by transistors in earnest, until the 1970s. 6V6 is the designator for a vacuum tube introduced by Radio Corporation of America RCA United States in late 1937. ... Assorted discrete transistors A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. ...

Further testimony for this device's success would be even simpler: the 6L6GC version is still being manufactured and used, primarily in guitar amplifiers. Manufacture continues in Russia (2 factories), China (2 factories), Slovakia and Serbia. Thus, the 6L6 has enjoyed one of the longest active lifetimes of any electronic component; almost 70 years. This article or section does not adequately cite its references or sources. ... Anthem Serbia() on the European continent() Capital (and largest city) Belgrade Official languages Serbian 1 Recognised regional languages Hungarian, Croatian, Slovak, Romanian, Rusyn 2 Albanian 3 Government Semi-presidential republic  -  President Boris Tadić  -  Prime Minister Vojislav KoÅ¡tunica Establishment  -  Formation 9th century   -  First unified state c. ...

References

• Stokes, John (1982). 70 years of radio tubes and valves. NY: Vestal Press, 71-72. 
• Thrower, Keith (1982). History of the British radio valve to 1940. MMA International, 59. 
• Barbour, Eric (1996). "History of the 6L6". Vacuum Tube Valley (4): 3. 
• Schade, O. H. (February 1938). "Beam Power Tubes". Proc. of IRE. 

External links

• TDSL Tube data [6L6]
• The 6L6-GC / 5881
• A 6L6 Classic