The video signal from a camera tube is amplified by the camera control unit, which processes and strengthens the signal before display.
The video signal produced by the camera tube is amplified by the camera control unit. Neither the output phosphor, the electron gun, nor the TV monitor are responsible for amplifying the video signal. The camera control unit processes and amplifies the signal coming from the camera tube before it's sent to be displayed on the monitor. In the context of CRTs (cathode ray tubes), the electron gun is used to accelerate and direct electrons towards the screen which, upon contact with the phosphors, emit the light that forms the image.