Guided Tour
The Development of Tubes


Room Selector:   Previous Room    The Beginnings of Radio and the Technology to build on: 1923-1933    The Development of Tubes    Radio Broadcasting in the Third Reich: 1933-1939    From Gramophone to CD    Radio Broadcasting during World War II    Post-War Era    Sender der Post-War Era, UKW    The Fifties    From Magnetophone to Tape Recorder    Radio and TV in the German Democratic Republic    History of Television    From the Sixties to the Present and the Future    Next Room


Nowadays, electronic tubes have been practically replaced in full by semiconductors (transistors and ICs) in radio and TV technology.

Rapid development came about by fundamental technological achievements by Edison (1883)-discovering thermionic emission-, Lenard (since 1890) -working with cathode rays-, Richardson (1903) -research into emission and thermodynamics- and Wehnelt (1904) -learning about particularly high emission capabilities of alkaline-earth oxides. Fleming (1904) was the first to use electron discharge as a rectifier, Lenard brought out a publication (1903) about a test arrangement using a grid between cathode and anode to control speed and intensity of the electron current.

Von Lieben and his colleagues Reisz and Strauss discovered (1906) the importance of intensity control of cathode rays for amplifying purposes. Their tubes were filled with mercury vapour and equipped first with a magnetic field regulator and as of 1910 with a grid control. In 1907, De Forest applied for a patent in the US for a three-electrode tube and called it »Audion«. These were the most important steps to introduce electronic tubes to telecommunications engineering.

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Loewe Triple Tube 3NF

The »Lieben consortium« (AEG, Siemens, Telefunken and Felten & Guilleaume) was to make commercial use of the von Lieben patents. Prof. Pirani (Siemens) and Dr. Rukop (Telefunken) quickly realised that instead of mercury vapour fillings the high-vacuum tube would produce a better amplifier module. To produce such a sound high vacuum, Langmuir (1913), Schottky (1914) and Dushman (1915) all invested much comprehensive research before and during World War I. It was not until after the war when Barkhausen, Möller, Rukop and Schottky published their comprehensive basic research work.

The injection grid in the form of a space-charge grid (Schottky 1915, Langmuir 1918) and protection or screen grid (Schottky 1916) was already part of state-of-the-art tube technology in 1918.

The indirectly heated cathode appeared in 1915. Hull and Williams improved the screen grid tube in 1919. In 1926, Jobst suppressed the secondary electrons by introducing a decelerating grid, thus creating the fundamental technology for pentodes which was further refined by Telegen in the same year.

 Tube Production

The theoretical physics around basic tube technology were now under control. With regards to production engineering, it was still possible to further improve electronic tubes, in particular concerning higher performance, smaller component sizes as well as more suitable materials. With the appearance of the transistor in the fifties, however, the decline of electronic tubes could not be stopped any more.


Room Selector:   Previous Room    The Beginnings of Radio and the Technology to build on: 1923-1933    The Development of Tubes    Radio Broadcasting in the Third Reich: 1933-1939    From Gramophone to CD    Radio Broadcasting during World War II    Post-War Era    Sender der Post-War Era, UKW    The Fifties    From Magnetophone to Tape Recorder    Radio and TV in the German Democratic Republic    History of Television    From the Sixties to the Present and the Future    Next Room


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