Suppressor grid

The braking grid is an electrode in an electron tube. The braking grid ( grating 3), the fourth electrode of tubes with a plurality of bars, arranged between the cathode and anode in the electron tubes. On the suppressor grid is always followed by the anode.

Function

The object of the braking grid is struck out to guide the secondary electrons from the anode to the anode back. This is achieved in that the braking grid has electrically the same potential as the cathode. Often the braking grid is also connected within the tube firmly to the cathode. The primary electron beam of direct light emitted by the cathode, and then accelerated by the screen grid, electrons are practically unaffected by the braking grids. Only the much slower secondary electrons are ejected due to the high kinetic energy of the primary electrons from the anode can be pushed back by the brake to the anode grid.

The suppressor grid thus allowing operation with low anode voltages. Without the suppressor grid would ejected secondary electrons at low anode voltages, as can occur with large modulation, fly back to the screen grid, decrease the anode current and cause distortion. If the secondary electrons overheat the screen grid submitting their kinetic energy, the tube may be damaged.

Beam power tetrode

This tube is the suppressor grid as a beam - guide plate, which - similar to a mount in the photography - the electrons deflected in a limited area of the anode. The function is otherwise identical. This type of braking grid is used almost exclusively in power tubes and is designed to bypass royalties of the Philips patent on the pentode with conventional screen grid.

In the pictures below to see two tubes are very open system design. EF91 the braking grid has a normal in the conventional scroll structure, while in the PL802 a darker colored radiation plate can be seen. The light sheet with the two connecting webs is the anode.

A suppressor grid is used only in a pentode in a triode or tetrode it does not exist.

• Pentode

Beam Power Pentode PL802

EL84 SEL as Beam - Power version: Reflective cut in the anode plate shows the jet plate.

EL84 SEL as Beam - Power version: detectable only two spine couples radiant panel flap covers the cathode.