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Pentode symbol
elements from top to bottom
A: anode
G3: braking
grid G2: screen grid
G1: control grid
K: cathode
f: heating

A pentode is an electron tube with five electrodes .

History and characteristics

The pentode (five-pole tube) was invented in 1926 by Bernard Tellegen , an employee at the Philips research laboratory , and patented together with Gilles Holst .

In addition to the anode and cathode , the control grid and the screen grid of the tetrode , it has a cathode connected to the suppressor grid . This keeps the secondary emission of the anode away from the screen grid.

The flat characteristic curve of pentodes shows that the anode is shielded by the additional grid in such a way that a change in the anode voltage hardly has any influence on the anode current. It only depends on the grid pre-tension on the control grid:

This results in a much higher gain.

The beam pentode , which for licensing reasons was called the beam power tetrode , behaves in a similar way .


See also

Web links

Commons : Pentodes  - collection of images, videos and audio files

Individual evidence

  1. U.S. Patent 1,945,040