Beam deflection tubes are cathode ray tubes with an electron gun, a beam intensity control grid, a screen grid, sometimes a suppressor grid, and two electrostatic deflection electrodes on opposite sides of the electron beam, that can direct the rectangular beam to either of two anodes in the same plane. They can be used as two-quadrant, single-balanced mixers or (de)modulators with very linear qualities, their mode of operation 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. 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.
They need extensive shielding against external magnetic fields. The ballistic transistors currently under development employ a similar principle.
*7360 - Balanced modulator or product detector up to 100 MHz
*6AR8, 6JH8, 6ME8 - Analog television chroma signal demodulators used in color TV receivers
More elaborate applications of the principle include:
* 2H21 and 5593 - Magnetically controlled "Phasitron" phase modulator tubes used in early FM broadcast transmitters.
* 6090 - 18-channel analog demultiplexer for telecomms receiving channel banks, an electrostatic deflection field determines which one out of 18 anodes receives the electron beam controlled by a common grid
*6170 and 6324 - 25-channel analog multiplexer for telecomms transmitting channel banks, a rotating magnetic deflection field determines through which one out of 25 grids the electron beam passes to the common anode
* E1T - Trochotron with a fluorescent-screen readout
* QK329 - ''Square-law tube'' for use as a function generator in analog computers. A flat sheet beam is deflected across the anode which is partially covered by a parabolically stenciled screen "grid" that acts as the tube's output.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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