A channel 3/4 output was a common output selection for most audiovisual devices intended to be connected to a TV using a Radio frequency (RF) signal. This channel option was provided because it was rare to have broadcast channels three and four used in the same market. The choice allowed the user to select the unused channel in their area so that the connected device would be able to provide video and audio on an RF feed to the television without excessive interference from a broadcast signal.

It is common to have this type of RF output on video cassette recorders (VCRs) and DVD players.

First-generation video-game consoles commonly used this to connect to the television, which was used as the audio and video device for the game. In many cases, an RF modulator was used to take the composite output from the game and modulate it before sending the signal to the television.