Image: Lieben-Reisz vacuum tube

Description: A "Lieben-Reisz tube" (or "Lieben-Reisz-Strauss relay"), an early experimental amplifying vacuum tube developed by Austrian engineers Robert von Lieben and Eugen Reisz beginning in 1906 and a competitor to the Audion (triode) invented by Lee De Forest for the earliest amplifying vacuum tube. About 16 in (41 cm) tall and 4 in (10 cm) wide. It consisted of a partially evacuated glass envelope containing 3 electrodes: a heated platinum filament wire (bottom) coated with barium or calcium oxides which released electrons which were attracted to the positively charged anode wire (top), passing through a "grid" made of a perforated metal plate (center). As in the Audion, a small voltage on the grid could control a larger anode current, so the tube could amplify. The inventors claimed a voltage gain of 33. The tube had a small amount of mercury vapor in it, released by the pellet of mercury amalgam in the small U shaped tube on the lower left side, to reduce the high anode voltage of 220 V required when the tube was evacuated. These were used by Alexander Meissner in 1913 to build some of the first electronic oscillator circuits, which he used the same year in a historic radiotelephone experiment, transmitting 500 kHz AM voice signals 23 miles (36 km) from Berlin to Nauen, Germany. Since the tube was patented a few months before the Audion, Lieben sued De Forest for patent infringement, but ultimately lost due to the deep pockets backing the Audion. (Information from source text)
Title: Lieben-Reisz vacuum tube
Credit: Downloaded July 18, 2013 from John Ambrose Fleming (1919) The Thermionic Vacuum Tube and its Developments in Radiotelegraphy and Telephony, The Wireless Press, London, p. 134, fig. 72 on Google Books
Author: John Ambrose Fleming
Usage Terms: Public domain
License: Public domain
Attribution Required?: No