Technical Notes:
Page 5
All Italics Mine
Kevin O'Neill
TS=Translation Suspect
Now we regard the symbols for tubes with grids:
The grid, which lies next to the cathode, we named the control grid. It has the strongest influence on the change of the electron flow.
The next grid is called the screen grid. It prevents the pulling influence of the anode, through the control grid, on the electron cloud around the cathode from becoming too large. Authors Note: It also reduces the capacitance between the control grid and the plate helping to alleviate unwanted feedback.
The third grid, called the suppressor grid, suppresses the electrons rebounding from the anode. Striking electrons produce heat, thus the anode could become glowing and the tube goes defective.
Sometimes still more grids are used, so that one can steer the electron flow from two sides. so e.g. two incoming frequencies can mix and receive another output frequency.
In 1936 RCA succeeded a large jump, in technology? the suppressor grid which suppresses rebounding electrons from the plate, could by special physical arrangement of the grids reach the point where no electrons were lost between anode and screen grid and the tube became enormously more powerful. These tubes are known as Beam power tubes or Strahlbündelröhren.
