Scanned articles covering tube technology. Unless otherwise noted, these scans were done by John Atwood. Articles marked "*" were extracted from worldradiohistory.com (formerly americanradiohistory.com) scans. Listed chronologically.

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White 1923 The Thoriated Tungsten Filament - Summary of the development of the thoriated tungsten filament and its application to the RCA UV-201A and UV-199 tubes.

Warner 1923 Recent Developments in High Vacuum Receiving Tubes - Radiotrons Model UV-199 and Model UV-201-A * - The introduction of General Electric's "X-L tungsten filament" tubes, i.e. thoriated-tungsten filaments. The UV-201A replaced the pure tungsten UV-201, with 1/4 the filament current. The UV-199 was a new tube with low enough filament current to be run from dry cells. Both these these tubes made consumer broadcast receivers much more practical.

Muhleman 1926 Vacuum Tubes and Their Uses - An article from the Aug. 1926 issue of Radio News describing all the varieties of American receiving tubes. Note that these are all triodes.

Radio News 1926 A New Rectifier Tube for A-B-C Power Units - Radio News from Oct. 1926 describes Raytheon's BH rectifier - a gaseous rectifier that could supply 350 volts at 85 mA. This is the predecessor of the 0Z4. The article claims it can supply A, B, and C power, but this is stretching things - the C (bias) voltage is derived from a back-bias resistor and the A (filament) voltage can only supply type 199 tubes in series.

Harris 1927 A New Electron Tube - Sylvan Harris describes Hull's "shielded grid" tetrode (originally devised by Schottky in Germany). This evolved into the types 22 and 24 tetrodes, which revolutionized RF and IF amplifier design - eliminating the need for neutralization. From Radio News, July 1927.

Millen 1927 The Raytheon A Rectifier - James Millen describes the Raytheon "A" rectfier, an electrolytic rectifier designed to be used in an "A eliminator", i.e. to supply the 6 volts needed to run the 01A-based radios of the day. Note that a small storage battery was still required for hum filtering. From Radio News, Aug. 1927.

Radio News 1928 The Shielded-Grid Tube at Last Arrives - Radio News from Jan. 1928 describes the first American shield-grid tetrode in some detail. Oddly, the type number of the tube (UX-222) is not mentioned.

Rockwood & Thompson 1928 Part 1 * and Rockwood & Thompson 1928 Part 2 * Application of the 4-Electrode Receiving Tube - The first widely-available American tetrode, the UX-222, also called the "screen-grid tube". This had the same 5 volt filament as the UX-201A. The tetrode and later the pentode revolutionized radio design, since no RF neutralization was needed and the gain per stage was higher than triodes.

Weaver 1929 A High-Power Output Tube-The 250 - The factors that went into the design of the 250 - the first American high-power audio triode. It got limited use, due to the need for 450 volts for maximum power. It was quickly overshadowed by the 250 volt UX-245.

Engel 1929 Engineering Features of the UX-245 - An audio triode that put out 1.6 watts at 250 volts. This was the dominant radio output tube until the advent of the 47 pentode and, later, the 2A3 triode.

Kusunose 1929 Calculation of Characteristics and the Design of Triodes * - A derivation of triode characteristics from the physical structure.

Van Der Mel 1933 The 2B6 - A Duplex Triode - An alternative to the power pentode: a cathode-follower directly driving a high mu triode in class A₂ mode. Not appreciably better than a pentode - this was likely done to get around the pentode patents.

Salzberg & Burnside 1935 Recent Developments in Miniature Tubes - Describes the need for, and the development of the VHF "acorn" tubes. Originally published in the Proceedings of the I.R.E. in Oct. 1935.

Harries 1936 The Anode to Accelerating Electrode Space in Thermionic Valves * - A clear description of the development of the "critical-distance tetrode", where the correct spacing of the screen grid to the plate produces a negative potential that emulates the supressor-grid of the power pentode. This is the basis of the American "beam-power tube".

Calpine 1936 Conditions in the Anode Screen Space of Thermionic Valves - An analytic explanation of the Harries "critical-distance tetrode" described above.

Germeshausen & Edgerton 1937 The Strobotron * and White et al 1937 The Strobotron II * - The Strobotron was a cold-cathode neon-based strobe light that could also be used as a fast high-current trigger tube. It was used in the first generation of the General Radio "Strobotac".

Benjamin et al 1937 Modern Receiving Valves-Design and Manufacture * - Details on the state of the art in receiving tube design and production in 1936 at M.O. Valve Co., Ltd. The last pages are missing.

Schade 1938 Beam Power Tubes - classic 1938 article by O.H. Schade of RCA on the requirements of audio amplifier tubes and how the beam power tube (6L6) is the best solution. Even if you are only into triodes, this is worth a read, since it combines a good "requirements document" for audio amplifiers along with the electron physics of how beam power tubes operate. Originally published in Proc. of the I.R.E., Feb. 1938, this was scanned from the RCA Electron Tubes Vol. I (1935-1941), published by RCA Review in 1949. 45 pages.

Harries 1938 Critical Distance Valves and Beam Tetrodes_letter * - J.H. Owen Harries, the inventor of the critical-distance tetrode in 1931 stakes his claim that the recently-announced RCA 6L6 "beam power tube" is essentially the same as the critical-distance tetrode, although Harries' tube did not use aligned control and screen grids.

Salzberg & Haeff 1938 Critical Distance Values and Beam Tetrodes_letter * - The engineers from RCA defend their analysis of the space-charge effect in beam tetrodes, in response to Harries' letter above.

Prakke et al 1939 A New All-Glass Valve Construction * - Researchers from Philips describe their new "all-glass" tube construction, as used in the EF50 RF pentode. This is essentially a 9-pin version of the 8-pin loctal tube developed by Sylvania in the US. Which came first? Did Philips and Sylvania colaborate?

Jonker 1939 Part 1 * and Jonker 1939 Part 2 * Pentode and Tetrode Output Valves * - A detailed analysis by Philips (the holder of the pentode patents) of the pentode and beam tetrode as used in audio output stages. They show that the beam tetrode is less perfect than the pentode at low plate voltages. They propose that the optimum design uses the supressor grid of the pentode as well as critical-distance spacing.

Fremlin 1939 Calculation of Triode Constants * - Comparing the equations for triode constants with experimental results. This includes an analysis of the case where the grid-cathode spacing is smaller than the grid pitch - a source of distortion, in some cases. Originally published in the Philisophical Magazine and Journal of Science. A correction by S. Rodda is here: Rodda 1939 Note on Fremlin Triode Constants Paper

Smith & Schooley 1940 Development and Production of the New Miniature Battery Tubes - Describes the first set of 7-pin miniature tubes, intended for portable AM radios: the 1R5, 1T4, 1S5, and 1S4. These battery types were used extensively in World-War II pack and hand-held radios. Originally published in the April 1940 issue of RCA Review.

Millman & Moskowitz 1941 Tracing Tube Characteristics on a Cathode Ray Oscilloscope * - A simple circuit for doing dynamic curve tracing. Jacob Millman was my senior advisor at Columbia Engineering School. He retired the year I graduated, 1976.

Howard 1941 Ceramics in Valve Construction * - A report on ceramic tube construction in Germany. The Germans were way ahead of America and the UK; the tube construction described didn't happen in America until the mid-1950s.

Hall & Howe 1942 Some Aspects of Radio Valve Manufacture * - A good summary of glass receiving tube manufacturing as done at The M.O. Valve Co, Ltd.

FM 1942 Wartime Tube Revisions * - The War Production Board (WPB) orders manufacturers to cease making 289 obsolete tube types. Some are truely obsolete (00A, 1B4, etc.), but most are obsolete versions of existing types (6K7G, 7A7LM, etc.). Some would still prove useful (6U5, 12V loctals, 5T4, 6W6GT) and would be made later. Also a request by the Navy to only use tubes on the "Vacuum Tubes for Use in New Equipment" approved list.

Harries 1942 Secondary Electron Problems in Beam Tetrodes * - A review of the "critical-distance" tetrode, i.e. the beam tetrode such as the 6L6, by its inventor, J.H. Owen Harries.

Jervis 194- Amplification Chart - From a collection of articles from Electronics. No date, but likely from the 1940s. Equations and a nomograph for determining amplification factor ("mu") from a tube's geometry.

Harries 1944 Secondary Electron Radiation - Very detailed summary of the physics of secondary emission. On the second-to-last page is the little-known history of the "critical-distance" tetrode (called a beam-power tube by RCA) and some issues on how it works. Originally published in the Sept. 1944 issue of Electronics, this scan is from a compilation of articles from Electronics.

Mouromtseff et al 1944 Review of Demountable vs Sealed-off Power Tubes - Demountable tubes are ones that can be easily taken apart to be repaired. Generally these are only of the very high power types. From the Nov. 1944 issue of the Proceedings of the I.R.E..

Rodda 1945 Space Charge & Electron Deflections in Beam Tetrode Theory Part 1 *
Rodda 1945 Space Charge & Electron Deflections in Beam Tetrode Theory Part 2 *
Rodda 1945 Space Charge & Electron Deflections in Beam Tetrode Theory Part 3 * - A three-part article that does a deep theoretical dive to explain the behavior of "critical-distance" or beam tetrodes.

Swedlund 1945 Improved Electron Gun for C-R Tubes * - The evolution of CRT electron gun design at RCA.

Rodda 1946 Beam Tetrode Characteristics * and Rodda 1946_letter Beam Tetrodes_letter * - An analysis of the effect of the retarding field of the space charge between the screen grid and the plate in a beam tetrode. The letter is a refinement at low plate voltages.

Heins 1946 Hydrogen Thyratrons * - Describes the development of the 4C35 and 5C22 hydrogen thyratrons. The bulk of the article is actually on radar line modulator design.

Espersen 1946 Fine Wires in the Electron-Tube Industry * - A summary of the uses of wire in the various aspects of tube manufacturing. Includes a nomograph for designing tungsten filaments.

Spitzer 1946 Induction Heating in Radio Electron-Tube Manufacture * - A summary and analysis of RF induction heating in transmitting tube manufacturing.

McCallum 1946 Pentodes and Tetrodes Operating as Triodes * - A chart that compares the power output and power sensitivity of audio power triodes and triode-connected tetrodes and pentodes. Not-shown, the Western Electric 300B, would fall very close to the "DO.24". The British sure had some nice directly-heated triodes!

Yeh 1946 The Effect of Grid-Support Wires on Focusing Cathode Emission * - An analysis of the effect of grid-support wires in tubes.

Gorham 1947 Electron Tubes in World War II * - A summary of the advancements in tube technologies and tube types that occured during World War II from an American perspective.

Berthilllier 1947 The Manufacture of Photo-Electric Cells * - A translation of a French article describing the manufacturing methods to make cesium oxide and antimony-cesium cathode photocells.

Dailey 1948 Designing Thoriated Tungsten Filaments * - Complete equations for designing thoriated tungsten filaments.

Wood 1948 Positive-Grid Characteristics of a Triode * - An effort to predict the behavior of triodes in the positive-grid region. Experimental results somewhat match theory.

Jacobs et al 1948 Relationship Between Emission Constant and Apparent Work Function * - The correlation between work function and the emission constant is established using specially-made filamentary test diodes.

Davies 1949 Quality Control in Radio-Tube Manufacture * - A detailed description of the quality-control methods used at General Electric's Owensboro (ex Ken-Rad) plant, both in-process and of finished tubes.

McCormack 1949 A Standard Diode for Cathode-Core-Material Tests * - A description of and test methods for a standard diode intended to evaluate nickel cathode materials. This was done for the ASTM Diode Committee.

Acker 1949 Testing Cathode Materials in Factory Production * - More details on evaluating nickel cathode materials according to the ASTM Diode Committee's work (see McCormack, above).

Jacobs & Wolk 1949 Microanalysis of Gas in Cathode Coating Assemblies * - Experiments to determine what gasses are evolved during cathode activation.

Adler & Haase 1949 The 6BN6 Gated Beam Tube - A two-part article on the concept and design of the 6BN6 gated-beam tube. Adler prototyped the tube at Zenith Radio, and Haase reduced it to practice at General Electric. From the Proceedings of the National Electronics Conference, Vol. V, Sept. 1949.

Diemer & Jonker 1949 Low-Distortion Power Valves * - These Philips researchers explore ways of reducing distortion in power pentodes. Their results: aligned control and screen grids and electrodes to control the electron flow towards the middle of the plate are very close to Philips' chief competitor: the beam tetrode!

Rogers 1950 Aligned-Grid Valves * - Experimental results of varying the control-grid to screen grid spacing in aligned-grid tubes, such as in beam tetrodes. Minimum screen current results at smaller grid spacing than previously thought.

Leferson 1950 Application of DC Pulsers to Measure Vacuum Tube Characteristics * - Using a radar-type line pulser to characterize very high-power transmitting tubes.

Espe, Knoll & Wilder 1950 Getter Material for Electron Tubes - An article from Oct. 1950 Electronics. Everything you wanted to know about getters. Extensive bibliography.

Bird 1951 The Measurement of Microphony in Valves * - The use of acoustic frequency sweeps to analyze microphonics in vacuum tubes.

Espe & Steinberg 1951 Aluminum-Clad Iron for Electron Tubes - Description of the development of aluminum-clad iron, called "P2 Iron" by its German inventors. This is the grey-colored plate, which replaced the black plates of carbonized nickel. This was crucial for Axis tube manufacturing during World War II: (from the article): "It has been estimated that the Middle-European Electron Tube industry, during the years 1936 to 1944, saved about 500 tons of nickel by the use of P2-Iron". An important article.

Bounds & Briggs 1951 Nickel Alloys for Oxide-Coated Cathodes * - Detailed descriptions of nickel refining and processing and the effects of various impurities on the behavior of oxide-coated cathodes. Good info.

Poehler 1952 The Influence of the Core Material on the Thermionic Emission of Oxide Cathodes * - The effects of various alloying elements on oxide-coated cathode behavior.

Espersen 1952 The L-Cathode Structure * - A comparison of the L-Cathode, developed by Philips, with other existing cathodes. This "dispenser-type" cathode has long life and high current capabilities.

Ayer 1952 Use of Thoriated-Tungsten Filaments in High-Power Transmitting Tubes * - The factors in using thoriated-tungsten filaments in very high power tubes (Ep > 5 KV). These tubes previously used pure tungsten filaments which were very inefficient.

Dunn 1952 Screen Dissipation of Pentodes_letter * - A letter in Wireless Engineer that describes how to optimize screen voltage and dissipation in pentodes.

Benson 1952 A Study of the Characteristics of Glow-Discharge Voltage Regulator Tubes Part 1 *
Benson 1952 A Study of the Characteristics of Glow-Discharge Voltage Regulator Tubes Part 2 * - A two-part article that carefully analyzes the behavior of gas regulator tubes. Mostly British types are covered, but the VR105 (0C3) and VR150 (0D3) are included.

Shelton & Wade 1953 Corona Discharge Tubes for Voltage Stabilization * - Instructions for making corona discharge tubes as well as analysis of their behavior. These tubes can serve as shunt regulators for voltages of 300 volts and higher. In America, these tubes were mainly made by Victoreen.

Grey & Jenkins 1954 Electrophoresis in the Valve Industry * - The use of electrophoresis to apply insulating coatings to filaments, heaters, etc. in vacuum tubes.

Jones 1954 Voltage Regulator Tubes - A brief summary of the gaseous voltage regulator tube. A list of American types are given. This came attached to RCA Application Note AN-161.

Jones 1954 Tube Envelope Temperature - The bulb temperatures vs power for various miniature and subminiature tube envelopes, and reasons for keeping the temperature low. This came attached to RCA Application Note AN-161.

Rowe & Welch 1954 Developments in Trustworthy-Valve Techniques - This article comes from S.T.C. in England and describes their efforts to make what Americans would call ruggedized or high-reliability tubes. Details on reducing noise, both random and microphonic, in tubes. From the Sept. 1954 issue of Electrical Communication.

Walsh 1955 Progress in Electron Tube Reliability - From Electrical Manufacturing. Analyzes the problems of tube reliability and describes improvements. References the work of ARINC (Aeronautical Radio, Inc.) and the Defense Department's AGET (Advisory Group on Electron Tubes). Describes tubes designed for automatic assembly and the RCA Special Red tubes.

Redston 1956 The Control of Thermionic Valve Envelope Quality by Thermal Shock Testing * - Detailed description of using thermal shock tests to improve the reliability of glass tube bases.

AE of AGOET 1956 Heater-Cathode Leakage - Author: "The Application Engineers of the Advisory Group on Electron Tubes". The causes and mitigation of heater-cathode leakage. Article reprinted and distributed by RCA, Tube Division.

Espersen & Rogers 1956 Studies on Grid Emission - A paper from the IRE Transactions on Electron Devices on grid emission due to vaporized barium oxide and other contaminants. Extensive details on the experimental methods used. Key results: gold plating helps a lot but titanium grids are by far the best.

Wyman & Kuhnapfel 1957 Metal Ceramic Tubes to Withstand 500C and High Vibration * - Super-rugged metal-ceramic tubes by Bendix's Red Bank Division. These were never widely used.

Horsting 1958 Electronic Materials - From the book Vacuum Metallurgy, edited by Rointan F. Bunshah, by Reinhold Publishing Corp., 1958. The use of vacuum techniques in preparing metals used in vacuum tubes.

Bowe 1959 What Cathode is Best for the Job - Factors for selecting the type and material for vacuum tube and CRT cathodes. From the April 1959 issue of Electronic Industries.

TI Metals & Controls 1959 GE 6L6GC General Plate - Copper-cored Aliron * - An advertisement from General Plate (a division of Texas Instruments) touting its 5-layer plate material that spreads the heat, allowing higher plate dissipation ratings.

Seymour 1960 Assessment and Control of Cathode Interface Impedance * - A good overview of the problems of cathode interface and ways to measure it.

Hasset 1961 The Materials and Shapes of Vacuum Tube Heaters - The configurations and manufacturing techniques for vacuum tube heaters. From the Dec. 1961 issue of Electronic Industries.