In a simple 2 stage CW transmitter, the transistor in the second stage would act as:

A simple two-stage CW (Continuous Wave) transmitter is built using two primary functional blocks: a master oscillator and a final amplification stage. The first stage contains the master oscillator, which generates the continuous wave RF signal at the desired frequency. The second stage takes that relatively weak signal from the oscillator and boosts its power to a level suitable for transmission to the antenna. Therefore, the transistor in this second stage functions as a power amplifier. While some transmitter stages can be designed to multiply frequencies, in a basic two-stage design, the fundamental role of the stage following the oscillator is power amplification.