6L6 is the designator for a beam power tube introduced by Radio Corporation of America in April 1936 and marketed for application as a power amplifier for audio frequencies.[1][2] The 6L6 is a beam tetrode that utilizes formation of a low potential space charge region between the anode and screen grid to return anode secondary emission electrons to the anode and offers significant performance improvements over power pentodes.[1] The 6L6 was the first successful beam power tube marketed. In the 21st century, variants of the 6L6 are manufactured and used in some high fidelity audio amplifiers and musical instrument amplifiers.
In the UK, three engineers at EMI (Isaac Shoenberg, Cabot Bull and Sidney Rodda) had developed and filed patents in 1933 and 1934 on an output tetrode that utilized novel electrode structures to form electron beams to create a dense space charge region between the anode and screen grid to return anode secondary electrons to the anode.[3][4] The new tube offered improved performance compared to a similar power pentode and was introduced at the Physical and Optical Societies' Exhibition in January 1935 as the Marconi N40.[5] Around one thousand of the N40 output tetrodes were produced, but MOV (Marconi-Osram Valve) company, under the joint ownership of EMI and GEC, considered the design too difficult to manufacture due to the need for good alignment of the grid wires.[6] As MOV had a design-share agreement with RCA of America, the design was passed to that company.[6][7]
Top view cross-section showing typical 6L6 type electrode structures and beam formation
The metal tube technology utilized for the 6L6 had been developed by General Electric and introduced in April 1935, with RCA manufacturing the metal envelope tubes for GE at that time.[8] Some of the advantages of metal tube construction over glass envelope tubes were smaller size, ruggedness, electromagnetic shielding and smaller interelectrode capacitance.[9] The 6L6 incorporated an octal base, which had been introduced with the GE metal tubes. The 6L6 was rated for 3.5 watts screen power dissipation and 24 watts combined plate and screen dissipation.[10] The 6L6 and variants of it became popular for use in public address amplifiers, musical instrument amplifiers, radio frequency applications and audio stages of radio transmitters.[11] The 6L6 family has had one of the longest active lifetimes of any electronic component, more than 80 years. As of 2021, variants of the 6L6 are manufactured in Russia, China, and Slovakia.
Variationsedit
The voltage and power ratings of the 6L6 series were gradually pushed upwards by such features as thicker plates, grids of larger diameter wire, grid cooling fins, ultra-black plate coatings and low loss materials for the base. Variants of the 6L6 included the 6L6G, 6L6GX, 6L6GA, 6L6GAY, 6L6GB, 5932/6L6WGA and the 6L6GC. All variants after the original 6L6 utilized glass envelopes. A "W" in the descriptor identified the tube as designed to withstand greater vibration and impact. A "Y" in the descriptor indicated that the insulating material of the base was .
Applicationedit
The high transconductance and high plate resistance of the 6L6 requires circuit design that incorporates topologies and components that smooth out the frequency response, suppress voltage transients and prevent spurious oscillation.[12]
Characteristicsedit
Anode characteristics with screen grid (grid 2) voltage as parameterAnode characteristics with the screen grid (grid 2) connected to the anode (i.e. used as a triode)
^ abJ. F. Dreyer Jr., "The Beam Power Output Tube", New York: McGraw-Hill, Electronics, April 1936, pp. 18 - 21, 35
^RCA Manufacturing Co. Inc., "Here is the New RCA 6L6 Beam Power Amplifier", New York: McGraw-Hill, Electronics, May 1936, back cover
^Schoenberg, Rodda, Bull, Improvements in and relating to thermionic valves, GB patent 423,932, published Feb. 1935
^Schoenberg, Rodda, Bull, Electron discharge device and circuits therefor, US patent 2,113,801 published Apr. 1938
^Editors, "New Output Tetrode", New York: McGraw-Hill, Electronics, Feb. 1935, p. 65
^ abK. R. Thrower, British Radio Valves The Classic Years: 1926-1946, Reading, UK: Speedwell, 2009, pp. 125 - 126
^O.H. Schade, "Beam Power Tubes" Proc. I.R.E., Vol. 26, No. 2, Feb. 1938, p. 153
^Editors, "Metal Tubes for Receivers", Radio Engineering, April 1935, pp. 18 - 19
^Metcalf, Beggs, "All-metal receiving tubes, the manufacturing technique", New York: McGraw-Hill, Electronics, May 1935, pp. 149 - 151
^RCA, RCA 6L6 Beam Power Amplifier, RCA Manufacturing Co., Inc.
^Wholesale Radio Service Co., Lafayette catalog no. 76, New York: Lafayette Radio Corp., 1939, pp. 38, 90, 96
^L. C. Hollands "Circuit Design Related to Tube Performance", New York: McGraw-Hill, Electronics, Mar. 1939, pp. 18 - 20
External linksedit
TDSL Tube data [6L6]
Electron Tube Data sheets: Several 6L6 datasheets from various manufacturers
Kurt Prange. (PDF) (PDF). Archived from the original (PDF) on 2014-02-21. Retrieved 2014-02-16.
Reviews of 6L6 tubes
May 08, 2024
designator, beam, power, tube, introduced, radio, corporation, america, april, 1936, marketed, application, power, amplifier, audio, frequencies, beam, tetrode, that, utilizes, formation, potential, space, charge, region, between, anode, screen, grid, return, . 6L6 is the designator for a beam power tube introduced by Radio Corporation of America in April 1936 and marketed for application as a power amplifier for audio frequencies 1 2 The 6L6 is a beam tetrode that utilizes formation of a low potential space charge region between the anode and screen grid to return anode secondary emission electrons to the anode and offers significant performance improvements over power pentodes 1 The 6L6 was the first successful beam power tube marketed In the 21st century variants of the 6L6 are manufactured and used in some high fidelity audio amplifiers and musical instrument amplifiers 6L6A 6L6 tube manufactured by SylvaniaClassificationBeam power tetrodeServiceClass A amplifier class B amplifier class AB amplifier audio amplifiers Height4 25 in 108 mm Diameter1 438 in 36 5 mm CathodeCathode typeIndirectly heatedHeater voltage6 3Heater current900 mAAnodeMax dissipation Watts30Max voltage500 Specification listed is for type 6L6 GCSocket connectionsThe 6L6 Pinout metal versions had the shell connected to pin 1 Pin 1 n c Pin 2 Heater Pin 3 Anode Plate Pin 4 Grid 2 Screen Pin 5 Grid 1 control Pin 6 n c Pin 7 Heater Pin 8 Cathode amp beam forming platesTypical class A amplifier operationAnode voltage350 VAnode current54 mAScreen voltage250 VBias voltage 18 VAnode resistance5 kOhmsTypical class AB amplifier operation Values are for two tubes Power output55 WAnode resistance anode to anode 5 6 kOhmsAnode voltage450 VAnode current2 54 mAScreen voltage400 VBias voltage 37 VReferencesEssential Characteristics General Electric 1973 Contents 1 History 2 Variations 3 Application 4 Characteristics 5 Improved substitute 6 Similar tubes 7 See also 8 References 9 External linksHistory editIn the UK three engineers at EMI Isaac Shoenberg Cabot Bull and Sidney Rodda had developed and filed patents in 1933 and 1934 on an output tetrode that utilized novel electrode structures to form electron beams to create a dense space charge region between the anode and screen grid to return anode secondary electrons to the anode 3 4 The new tube offered improved performance compared to a similar power pentode and was introduced at the Physical and Optical Societies Exhibition in January 1935 as the Marconi N40 5 Around one thousand of the N40 output tetrodes were produced but MOV Marconi Osram Valve company under the joint ownership of EMI and GEC considered the design too difficult to manufacture due to the need for good alignment of the grid wires 6 As MOV had a design share agreement with RCA of America the design was passed to that company 6 7 nbsp Top view cross section showing typical 6L6 type electrode structures and beam formationThe metal tube technology utilized for the 6L6 had been developed by General Electric and introduced in April 1935 with RCA manufacturing the metal envelope tubes for GE at that time 8 Some of the advantages of metal tube construction over glass envelope tubes were smaller size ruggedness electromagnetic shielding and smaller interelectrode capacitance 9 The 6L6 incorporated an octal base which had been introduced with the GE metal tubes The 6L6 was rated for 3 5 watts screen power dissipation and 24 watts combined plate and screen dissipation 10 The 6L6 and variants of it became popular for use in public address amplifiers musical instrument amplifiers radio frequency applications and audio stages of radio transmitters 11 The 6L6 family has had one of the longest active lifetimes of any electronic component more than 80 years As of 2021 variants of the 6L6 are manufactured in Russia China and Slovakia Variations editThe voltage and power ratings of the 6L6 series were gradually pushed upwards by such features as thicker plates grids of larger diameter wire grid cooling fins ultra black plate coatings and low loss materials for the base Variants of the 6L6 included the 6L6G 6L6GX 6L6GA 6L6GAY 6L6GB 5932 6L6WGA and the 6L6GC All variants after the original 6L6 utilized glass envelopes A W in the descriptor identified the tube as designed to withstand greater vibration and impact A Y in the descriptor indicated that the insulating material of the base was Micanol Application editThe high transconductance and high plate resistance of the 6L6 requires circuit design that incorporates topologies and components that smooth out the frequency response suppress voltage transients and prevent spurious oscillation 12 Characteristics edit nbsp Anode characteristics with screen grid grid 2 voltage as parameter nbsp Anode characteristics with the screen grid grid 2 connected to the anode i e used as a triode Improved substitute edit5881Similar tubes edit6P3S 6P3S 6P3S E 6P3S E 7027aSee also edit6V6 KT66 KT88 6550 6CA7 EL34 List of vacuum tubesReferences edit a b J F Dreyer Jr The Beam Power Output Tube New York McGraw Hill Electronics April 1936 pp 18 21 35 RCA Manufacturing Co Inc Here is the New RCA 6L6 Beam Power Amplifier New York McGraw Hill Electronics May 1936 back cover Schoenberg Rodda Bull Improvements in and relating to thermionic valves GB patent 423 932 published Feb 1935 Schoenberg Rodda Bull Electron discharge device and circuits therefor US patent 2 113 801 published Apr 1938 Editors New Output Tetrode New York McGraw Hill Electronics Feb 1935 p 65 a b K R Thrower British Radio Valves The Classic Years 1926 1946 Reading UK Speedwell 2009 pp 125 126 O H Schade Beam Power Tubes Proc I R E Vol 26 No 2 Feb 1938 p 153 Editors Metal Tubes for Receivers Radio Engineering April 1935 pp 18 19 Metcalf Beggs All metal receiving tubes the manufacturing technique New York McGraw Hill Electronics May 1935 pp 149 151 RCA RCA 6L6 Beam Power Amplifier RCA Manufacturing Co Inc Wholesale Radio Service Co Lafayette catalog no 76 New York Lafayette Radio Corp 1939 pp 38 90 96 L C Hollands Circuit Design Related to Tube Performance New York McGraw Hill Electronics Mar 1939 pp 18 20External links editTDSL Tube data 6L6 Electron Tube Data sheets Several 6L6 datasheets from various manufacturers Kurt Prange 6L6GC Comparison of Current Made Tubes PDF PDF Archived from the original PDF on 2014 02 21 Retrieved 2014 02 16 Reviews of 6L6 tubes Retrieved from https en wikipedia org w index php title 6L6 amp oldid 1205530204, wikipedia, wiki, book, books, library,
