Beam deflection tube

They can be used as two-quadrant, single-balanced mixers or (de)modulators with very linear qualities.

Their mode of operation is similar to one-half of a Gilbert cell by applying an unbalanced signal f1 to the control grid and a balanced signal f2 to the deflection electrodes, then extracting the balanced mixing products f1 − f2 and f1 + f2 from the two anodes.

[1][2] Similar to a pentagrid converter, the cathode and the first two grids can be made into an oscillator.

Two beam deflection tubes can be combined to form a double-balanced mixer.

The ballistic deflection transistors currently under development employ a similar principle.