Which characteristic describes a vacuum tube functioning as a Class B amplifier?

Which characteristic describes a vacuum tube functioning as a Class B amplifier?

• A. Plate current flows 360 degrees with low efficiency
• B. Medium power output, with plate current flowing slightly over 180 degrees
• C. High efficiency with output distortion
• D. None of the above

Answer: (B)

A vacuum tube functioning as a Class B amplifier is characterized by plate current flowing slightly over 180 degrees. In a Class B configuration, the tube conducts during one half of the input signal cycle, meaning it is effectively on for about 180 degrees of the input waveform. This allows for medium power output while maintaining better efficiency compared to a Class A amplifier, where the plate current would flow continuously throughout the entire cycle. Class B amplifiers achieve higher efficiency levels, as they avoid the power loss associated with continuous conduction. However, it is important to note that the output stage may introduce some distortion due to the abrupt cutoff of the current, especially at the crossover point between the positive and negative halves of the waveform. This is distinct from Class A amplifiers, which tend to have lower distortion but at the cost of higher power consumption. The description of a Class B amplifier highlights this specific operational characteristic, reinforcing the identification of option B as accurate.

A vacuum tube functioning as a Class B amplifier is characterized by plate current flowing slightly over 180 degrees. In a Class B configuration, the tube conducts during one half of the input signal cycle, meaning it is effectively on for about 180 degrees of the input waveform. This allows for medium power output while maintaining better efficiency compared to a Class A amplifier, where the plate current would flow continuously throughout the entire cycle.

Class B amplifiers achieve higher efficiency levels, as they avoid the power loss associated with continuous conduction. However, it is important to note that the output stage may introduce some distortion due to the abrupt cutoff of the current, especially at the crossover point between the positive and negative halves of the waveform. This is distinct from Class A amplifiers, which tend to have lower distortion but at the cost of higher power consumption. The description of a Class B amplifier highlights this specific operational characteristic, reinforcing the identification of option B as accurate.