Pentode

The PENTODE , invented by Gilles Holst and Bernhard DH Tellegen in 1926, is an active electronic component of amplification with five electrodes, including three grids (control grid, screen grid and suppressor grid), as well as filament and cathode. The pentode (also called a "triple grid amplifier") was developed from the (closely related) Tetrode tube by adding a third (suppress) grid, which served to prevent instability and parasitic oscillations. The pentode has been extensively used in industrial equipment and in radio history.

Pentode