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Reference to tube amplifiers; solid state is similar:

Class A is biased in the middle of the most linear portion of the EgIp (grid voltage/plate current) curve. Plate current flows for 100% (360 degrees) of the time as long as the input signal doesn't drive the tube into cutoff. Least efficient but output is greater and is a perfect and undistorted larger "copy" of the input.

Class B is biased right at the cutoff point of the EgIp curve. Plate current flows for 180 degrees of the input signal. Quite a bit more efficient than Class A. Not suitable for audio amplifiers because the output is only 1/2 of the input signal.

Class C is biased "well beyond" cutoff. Plate current flows for MAYBE 90 degrees of the input signal. Not suitable for AM or SSB; fine for FM and CW, and many of the digital modes.

Then there are Class AB₁ and AB₂, biased somewhere between the most linear part of the EgIp curve and cutoff. Plate current flows for more than 180 degrees but not for the full 360.

<blockquote data-quote="Beetle" data-source="post: 597249" data-attributes="member: 1066">Reference to tube amplifiers; solid state is similar:Class A is biased in the middle of the most linear portion of the EgIp (grid voltage/plate current) curve.&nbsp; Plate current flows for 100% (360 degrees) of the time as long as the input signal doesn&#039;t drive the tube into cutoff. Least efficient but output is greater and is a perfect and undistorted larger &quot;copy&quot; of the input.Class B is biased right at the cutoff point of the EgIp curve.&nbsp; Plate current flows for 180 degrees of the input signal.&nbsp; Quite a bit more efficient than Class A.&nbsp; Not suitable for audio amplifiers because the output is only 1/2 of the input signal.Class C is biased &quot;well beyond&quot; cutoff.&nbsp; Plate current flows for MAYBE 90 degrees of the input signal.&nbsp; Not suitable for AM or SSB; fine for FM and CW, and many of the digital modes.Then there are Class AB₁ and AB₂, biased somewhere between the most linear part of the EgIp curve and cutoff.&nbsp; Plate current flows for more than 180 degrees but not for the full 360.</blockquote>

[QUOTE="Beetle, post: 597249, member: 1066"] Reference to tube amplifiers; solid state is similar: Class A is biased in the middle of the most linear portion of the EgIp (grid voltage/plate current) curve. Plate current flows for 100% (360 degrees) of the time as long as the input signal doesn't drive the tube into cutoff. Least efficient but output is greater and is a perfect and undistorted larger "copy" of the input. Class B is biased right at the cutoff point of the EgIp curve. Plate current flows for 180 degrees of the input signal. Quite a bit more efficient than Class A. Not suitable for audio amplifiers because the output is only 1/2 of the input signal. Class C is biased "well beyond" cutoff. Plate current flows for MAYBE 90 degrees of the input signal. Not suitable for AM or SSB; fine for FM and CW, and many of the digital modes. Then there are Class AB₁ and AB₂, biased somewhere between the most linear part of the EgIp curve and cutoff. Plate current flows for more than 180 degrees but not for the full 360. [/QUOTE]

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