A valve amplifier or tube amplifier is a type of electronic amplifier that makes use of vacuum tubes to increase the amplitude of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by solid state amplifiers during the 1960s and 1970s. Valve amplifiers are used for applications such as guitar amplifiers, satellite transponders such as DirecTV and GPS, audiophile stereo amplifiers, military applications (such as radar) and very high power radio and UHF television transmitters.
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