Valve Amplifier - Characteristics

Characteristics

Power valves typically operate at higher voltages and lower currents than transistors - although solid state operating voltages have steadily increased with modern device technologies. High RF power radio transmitters in use today operate in the kilovolt range, where there is still no other comparable technology available. (Power = volts x amps so high power requires high volts, high amps or high both)

Many power valves have good linearity but modest gain or transconductance. Signal amplifiers using tubes are capable of very high frequency response ranges – up to radio frequency. Indeed, many of the directly heated single-ended triode (DH-SET) audio amplifiers are in fact radio transmitting tubes designed to operate in the megahertz range. In practice, however, tube amplifier designs typically "couple" stages either capacitively, limiting bandwidth at the low end, or inductively with transformers, limiting the bandwidth at both ends.