Which of the following is NOT a stage found in a basic CW transmitter?

In the context of a basic continuous wave (CW) transmitter, the primary function involves generating a radio signal that can be modulated and sent out via an antenna. Each stage of the transmitter plays a critical role in this process. The oscillator is essential for generating the carrier wave, while the power supply provides the necessary energy to operate the various components of the transmitter. The antenna is crucial for radiating the generated signal into the air.

The microphone, however, is not typically a component of a basic CW transmitter. In traditional AM or FM transmitters, a microphone would be used to convert sound waves into electrical signals for transmission. In contrast, a basic CW transmitter typically generates a single frequency signal that is turned on and off, representing Morse code or other non-voice signals, rather than converting sound waves from a microphone. Thus, it does not include this stage, making it the correct answer to the question.