An RCA connector is a plug and a jack designed for use with coaxial cable for frequencies ranging from the very lowest up to several megahertz. An RCA connector is sometimes known as a phono plug and jack.
The male RCA plug consists of a central pin measuring approximately two millimeters (mm) in diameter, and an outer shell whose inside diameter is approximately six mm. The plug shell is slotted rather than threaded, to facilitate quick insertion to, and removal from, the female jack or receptacle. Contact is maintained by physical pressure between the slotted shell of the plug and the smooth cylindrical barrel of the jack. The plug shell is connected to the outer conductor, or shield, of the coaxial cable, normally at electrical ground. The center pin of the plug is connected to the cable center conductor, which carries the signal. In the jack, the barrel is grounded and the center hole is plated inside to conduct the signal.
RCA connectors are suitable for audio-frequency (AF) applications. They are also used in radio-frequency (RF) systems at low and medium frequencies, and at power levels up to approximately 100 watts. At higher frequencies or higher power levels, larger connectors are necessary. RCA connectors are designed for cables with small outside diameters (less than 6 or 7 mm) and are intended for indoor use only.