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The Saga of the Vacuum Tube
April 1946 Radio News Article

April 1946 Radio News
April 1946 Radio News Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio & Television News, published 1919-1959. All copyrights hereby acknowledged.

Here is the final installation of a-22 part series entitled "The Saga of the Vacuum Tube," by Gerald Tyne, that appeared in Radio News magazine in 1946. Part 1 was printed in March 1943. The collective contents, which covered the development of the vacuum tube from its conception to the end of World War I, could have been published as a stand-alone book. Author Gerald F. J. Tyne presented the series to trace the development which took place up to the end of World War I along a particular branch of the network of roads which led to the modern radio tube. He traced the evolution from studies of the interactions between heat and electricity as pursued by the early philosophers and by the physicists who followed them (Lee de Forest, et al). These limitations have been adopted in an attempt to report the work done in the years where there is a dearth of readily available published material. At the time this final article was written near the end of World War II, great strides had been made in vacuum tube technology that not only helped secure victory for Allied forces, but served as a springboard for fueling a booming economy in the post war years as households transitioned from a wartime to a peacetime existence that saw unparalleled growth in creature comforts, many of which used vacuum tubes.

The Saga of the Vacuum Tube Part 22

The Saga of the Vacuum Tube, April 1946 Radio News - RF Cafe

Fig. 234 - RE11 tube with ballast resistor. Photograph courtesy Bell Telephone Laboratories.

By Gerald F. J. Tyne

Research Engineer, N. Y.

Part 22. Concluding article of a historical series which has covered the development of the vacuum tube from its conception to the end of World War 1.

Not long after the EVE173 tube was put into production the system of nomenclature was changed and German receiving tubes were denoted by the prefix RE (= Rohre Empfanger), transmitting tubes by RS (= Rohre Sende), and two new prefixes came into being RG (= Rohre Gleichrichter) for rectifiers and RV (= Rohre Endverstarker) for output tubes.312

Probably the first of these tubes to be made in any quantity, 250 per day in 1918,313 was the RE11, shown in Fig. 234. This tube like most of its predecessors was used with an iron wire ballast resistor in the filament circuit and one of these ballast resistors is also shown in the figure_ This tube had a tungsten filament of about the same characteristics as the 52 EVE173 (.55 ampere at 2.8 volts), but operated at an anode voltage of 40 to 70 volts and had an amplification factor of 8 and mutual conductance of 120150 micromhos, slightly higher than that of the EVE173.314 It was a general purpose tube.

Another general purpose tube, bearing a closer resemblance to the EVE173, was the RE16 shown in Fig. 244. This was used chiefly as a detector for c.w. work.315 The extent of its use may be gauged by the fact that in the summer of 1918 Telefunken was producing them at the rate of 1000 per day.313 It had a filament which took 0.50.6 ampere at 4.0 volts. The usual anode voltage was 65 and the mutual conductance about 200 micromhos, the internal resistance being about 24,000 ohms. This tube had about the same anode characteristics as the French tube described in the preceding installment although it required less filament power. The normal anode current was about 1 milliampere.

Telefunken RS1 - RF Cafe

Fig. 235 - Telefunken RS1 vacuum tube. Reproduced from Telefunken Festschrift 1928.

Telefunken RS5 - RF Cafe

 Fig. 236 - Telefunken RS5 vacuum tube. Photograph courtesy R. McV. Weston and Electrical Communication.

TKD ST12 tube - RF Cafe

Fig. 237 - TKD ST12 vacuum tube.

Huth LE219 vacuum tube - RF Cafe

Fig. 238 - Huth LE219 vacuum tube, front and side views. Reproduced from Nespers' "Der Radio Amateur "-1924.

LeftSeddig vacuum tube - RF Cafe

Fig. 239 - LeftSeddig vacuum tube. Filament 0.56 ampere at 2.8 volts. Right Auer receiving tube.

Development of Telefunken RS17 vacuum tube - RF Cafe

Fig. 240 - Development of Telefunken RS17 vacuum tube. Reproduced from Niemann's "Funkentelegraphie fur Flugzeuge" 1921.

Siemens Schottky type vacuum tube - RF Cafe

Fig. 241 - Development of the SS (Siemens Schottky) type vacuum tube. Reproduced from "Veroffentlichungen aus dem Gebiete der Nachrichtentechnik"-1935.

RE20 vacuum tube - RF Cafe

Fig. 242 - Left RE20 vacuum tube. Right RE26 tube. Reproduced from Banneitz "Taschenbuch der drahtlosen Telegraphie"1927.

Space charge grid vacuum tube - RF Cafe

Fig. 243 - Development of the space charge grid vacuum tube. Reproduced from "Veroffentlichungen aus dem Gebiete der Nachrichtentechnik"1935.

Triode tubes were also made during this period by other German manufacturers, among them Huth,316 Seddig.317 and Auer.318 Some of these tubes are shown in Figs. 238 and 239. It will be observed that the Huth tube shown was of plane parallel electrode construction. Earlier Huth tubes used a cylindrical element assembly but Huth was compelled to change to the plane electrodes because of patent difficulties, The earlier Huth tubes bore RE numbers similar to those of Telefunken, but those with plane electrode systems were designated by LE numbers.319 It is during this period also that we find considerable research effort being expended in Germany on the multiple electrode tube. It was early realized by Dr. Walter Schottky320 of the Siemens & Halske Company that there were limits to the amplification which could be attained by the use of a triode and he set out to devise a tube which would be capable of high amplification with the low anode potentials available in Army field equipment.

Accordingly he investigated the possibility of modifying the high vacuum triode by the insertion of additional electrodes. He patented the space charge principle in 1915321 and the "protective network" type in 1916.322 His first patent on a multiple electrode tube was German patent D.R.P. 300617, issued June 1, 1916, and covered a tube designated by Schottky as a "protective network" (Schutznetz) type. Another patent, D.R.P. 300192 issued June 21, 1916, covered another double grid arrangement. Patent D.R.P. 300191 for a tube having a space charge grid in which both grids were characterized by being composed of strips of sheet metal placed with edges toward the cathode was issued on January 24, 1917.

The first production of the multiple electrode Schottky tubes were tetrodes of the protective network type, known as the SSI, SSII, and SSIII. While the protective network was a grid inserted between the control grid and the anode these tubes differed from the modern "screen grid" type in that no attempt was made to use the additional grid to minimize the electrostatic capacitance between the anode and the control grid. This difference is relatively unimportant for low frequency work, but is of great importance in high frequency applications. As Schottky himself pointed out, his tubes were not suitable for use at high frequencies.323

The early model and later quantity production type of the SS tubes are shown in Fig. 241. Fig. 241 (left) shows the earliest construction of this type. The electrode assembly was cylindrical, the grids were of the "squirrel cage" type, and a double press was used. The electrodes were slotted so that it was possible to insert the filament assembly into the electrode assembly after fabricating the two separately. Fig. 241 (right) shows a single-ended production type tube with glass "star" as the support of the electrode system.

The SSI was first manufactured in 1917. It had a filament which operated with 0.4 ampere at 2.4 volts. The anode potential was 35 volts and the potential of the protective network was 15 volts. When so operated it gave an amplification of about 50 and had a mutual conductance of 250 micromhos.

The SSII, also known as the RE97,324 was a lower powered, lower gain tube, operating with a filament current of 0.24 ampere at 1.9 to 2.2 volts, and with 10.5 volts on both the anode and the protective network. It had an amplification factor of 30 and mutual conductance of 30 micromhos. The SSIII, also known as the RE114, drew a filament current of 0.55 ampere at 3.2 volts and operated with 120 volts on the anode and 45 volts on the protective network. It had an amplification factor of about 100 and a mutual conductance of 250 micromhos. The internal resistance was about 250,000 ohms.

Tubes of the space-charge grid type were also manufactured during this period. Typical examples of the smaller ones are the Telefunken RE20 and RE26, shown in Fig. 242. Both these tubes had tungsten filaments operating at 0.5 ampere at 2.8 and 4.0 volts respectively. They operated at 12 to 18 volts on the anode and space charge grid, had an amplification factor of about 8 and mutual conductance of about 350. Since they had 5 prong bases they required special sockets.

Larger tubes of the space-charge grid type were also developed and Fig. 243 shows the development series of one such tube. Figs. 243(A) and 243(B) show the early models. The grids are of wire netting. The space charge grid is small in diameter while the control grid is very close to the anode. Fig. 243(C) shows a production type tube of the vintage of 1919, still with the double press, Fig. 243(D) illustrates the final construction which was put into production about 1920.

Combination space charge and protective network tubes with three grids were also developed and some of these are shown in Fig. 245. The tube at the left is an experimental type with three grids using a double press and slotted electrodes. That at the right is a production type similar to the SS series.

In parallel with the work on receiving tubes Telefunken and the other German concerns had also been carrying on the development of transmitting tubes. The first of these to be made in quantities was the RS1, shown in Fig. 235. It gave about three watts output when operated with 400 volts on the anode, in the apparatus in which it was first used, an Army trench transmitter. It was capable of operation at higher anode voltages, and at 600 to 800 volts would put out 10 to 20 watts.325 The RS2 and RS3 were of no particular importance. The RS4 was a higher powered tube giving 50 to 75 watts output at 1000 to 2000 volts on the anode, and had a filament which took 3 amperes at 9 volts. The RS5, shown in Fig. 236, was an RS4 with improved characteristics. It took a filament current of 3 amperes at about 8 volts. The successor to the RS4 was the RS17, the evolution of which is shown graphically in Fig. 240.

All these transmitting tubes were characterized by the excellent glass work shown in their internal construction. This construction was common to all of the small transmitter tubes of early German manufacture, and is again exemplified in the TKD ST12 shown in Fig. 237.326 This tube again shows the effect of metal shortages. The interior portion of the base, in which the connecting pins are mounted, is of wood and the shell is of iron, with a poor nickel plate.

This series of articles has been presented to trace the development which took place up to the end of World War I along a particular branch of the network of roads which led to the modern radio tube. It has attempted to trace the evolution from studies of the interactions between heat and electricity as pursued by the early philosophers and by the physicists who followed them. These limitations have been adopted in an attempt to report the work done in the years where there is a dearth of readily available published material.

In any field of human activity books and periodicals are published by and for those interested. Such was the case in the early days of radio, with which the vacuum tube is so inextricably bound up. Much of the widespread interest in radio in the United States may be traced to the band of eager enthusiasts who made up the amateur fraternity in the days before World War I. The ham of those days spent his spare, and often not-so-spare, cash, burned his midnight electricity, and experimented unceasingly to fathom the mysteries of transmission and reception. Much progress came from interchange of ideas and experiences with others of like inclination. But unlike the situation existing today the facilities for such interchange were very limited. Books and periodicals dealing with such matters were few and far between. Periodicals in particular were of limited circulation, aimed at the experimenter of high school age and pocketbook and, except in a few cases, were not deemed of sufficient importance to be included in the permanent files of public libraries. Few books were written, since the men who were doing the work were too busy doing it to write about it.

RE16 vacuum tube - RF Cafe

Fig. 244 - RE16 vacuum tube. The top is painted red. Reproduced from Nesper's "Der Radio Amateur"1924.


Schottky three grid vacuum tube - RF Cafe

Fig. 245 - Development of the Schottky three grid vacuum tube. Reproduced from "Veroientlichungen aus dem Gebiete der Nachrichtentechnik" 1935.

With the advent of broadcasting and the great increase in adult popular interest in radio there came into being a number of widely circulated periodicals, technical and popular, both here and abroad, which published large quantities of information on current radio and vacuum tube development. These were preserved in most libraries of any size and are usually available to the earnest student of vacuum tube history.

For this reason little space has been devoted to cold cathode, cathode ray, multigrid, and higher powered transmitting tubes, such as the silica envelope type made by Philips-Mullard, the water-cooled copper-to-glass seal type developed by Housekeeper, and the larger radiation cooled types. Information on these phases of development can be obtained from these sources by the student or collector who seeks information on a specific type, and its collation and republication here is considered unjustified.


312. Martin-"Telefunken Rohrentypen" Telefunken Zeitung, Vol. 4, No. 32/33, September 1923, pp. 5155.

313. Rukop, Hans"25 Jahre TelefunkenDie Teleftistkenrohren und ihre Geschichte" Telefunken Festschrift1928, p. 49.

314. Banneitz, F. "Taschenbuch d e r drahtlosen Telegraphie und Telephone" SpringerBerlin1927, p. 476.

315. Harper, A. E.`Amplifying Bulbs" QST, Vol. 4, No. 7, February 1921, pp. 2728.

316. Dr. Erich F. Ilnlh Gesellschaft fur Funk entelerlruphie.

317. (R.I.W.) Smithy, Wurzbnr.q.

318. Auer Studiengesellschaft fur elektrische Leuchtrohren.

319. Groskowski, J.'Qes launpes a plusieurs electrodes et leurs applications en radiotechnique" Etienne ChironParis1925, p. 125.

320. Schottky. W.' fiber Hochvakuum Verstärker III Teil Mehrgitterrohren" Archiv fur Elektrotechnik. Vol. 8, No. 9, December S. 1919, pp. 299328.

321. D.R.P. 310605, issued March 19, 1915.

322. D.R.P. 87745, issued May 31, 1916.

323. See reference 323, p. 320.

324. Polilalunn, R. und Gehrts .4."Werdegan,q einer Verstarkerrohre" Elektrische NacJarie1ilcitTeehnik, Vol. 2, No. 3, Illoreb 1925, pp. 6574.

325. See reference 316, p. 142.

326. "TED" is the trade mark of Suddeutsche Telefon, Apparate-, Kabel, und DrahtWerke, Nurnberg.

Note: the entire series of "The Saga of Vacuum Tubes" articles can be accessed on the American Radio History website in PDF format. Below, I have take taken the time to list and link to each edition containing parts 1 through 22, along with the pages on which they begin.

  • Part 1 of this especially-prepared series of articles giving the complete history and development of the radio vacuum tube. March 1943, p25.
  • Part 2 of this authoritative series, shows the tremendous amount of preliminary work that led to the discoveries of the radio tube. April 1943, p31.
  • Part 3 of this series covering the Edison era, illustrating many of his outstanding inventions and the problems encountered. May 1943, p26.
  • Part 4 covering the development of communications for wireless telegraph, using thermionic tubes for the first time. July 1943, p30.
  • Part 5 of the era of controversy between patent rights on thermonic tubes designed by de Forest, Fleming, Weagant and others. August 1943, p26.
  • Part 6 Covering the period daring which Dr. Lee de Forest urns at the height of his inventive career. Many of his tube patents are discussed. September 1943, p26.
  • Part 7 of the series, covering the period during which the first commercial grid-type Audion tube was manufactured for civilian use. October 1943, p26.
  • Part 8 Covering the period during which the elements of the triode tube were redesigned to obtain increased performance. November 1943, p26.
  • Part 9 The early constructional problems of the the Western Electric type-101 vacuum tube - covering its multiplicity of shapes and sizes. January 1944, p38.
  • Part 10 Covering the evolution of the vacuum tube through the years 1914 to 1918, as a result of the research work done by Western Electric. March 1944, p50.
  • Part 11 Covering a number of the unusual earlier constructed tubes that are of particular interest to many old timers. April 1944, p54.
  • Part 12 The period of increased activity in the wireless industry with Lee de Forest's development of suitable oscillator and detector tubes. June 1944, p52.
  • Part 13 Covering the developments by the General Electric Co. of higher power output alternators for use in the fields of telegraphy and telephony. September 1944, p46.
  • Part 14 Covering the development of the "Kenotron," "Pliotron," "Dynatron," and "Magnetron" by Drs. Langsnuir, Dushman, and Hull of the General Electric Laboratories, during the years 1913 to 1921. November 1944, p56.
  • Part 15 The early growth of the amateur fraternity, with the development and manufacture for public use of the Audion and crystal detector. January 1945, p54 (go to PDF p104 due to "Engineering Department" insert).
  • Part 16 The early manufacture and sale of the "Electron Relay" and other amateur tubes by Otis R. Moorhead. March 1945, p52.
  • Part 17 A study of repeater tube developments in local and long-distance telephonic transmissions. May 1945, p58.
  • Part 18 Continuing our study of telephone repeater-tube developments in this country and abroad and their application during the first World War. July 1945, p56.
  • Part 19 Covering developments and applications of tubes in England from 1911 through World War 1. September 1945, p54.
  • Part 20 Continuing the study of the evolution of the vacuum tube and the many mechanical problems that were confronted in their manufacture during World War 1. November 1945, p51.
  • Part 21 Vacuum tube developments that were carried on in France and Germany during the first World War. February 1946, p54.
  • Part 22, Concluding article of a historical series which has covered the development of the vacuum tube from its conception to the end of World War 1. April 1946, p52



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