balanced/unbalanced (wiring) (Balun)
Balun is a made-up word from Balanced and Unbalanced. They are balancing elements or symmetry transformers that are used in cabling, in high- frequency technology in transmission systems, in network technology and in audio technology. Baluns convert unbalanced signals into balanced signals and provide impedance and symmetry matching of different transmission media. They match balanced lines such as TP cables to unbalanced coaxial cables.
Baluns usually contain simple miniature transformers that convert balanced signals into unbalanced signals or vice versa, thus providing matching between TP cables and coaxial cables. They suppress occurring common- mode interference voltages in the signal lines and avoid cladding waves on the unbalanced coaxial cable.
In high-frequency technology, baluns are used, among other things, in antenna technology when connecting a balanced antenna, such as a dipole antenna, to a coaxial cable. In addition to symmetry matching, baluns are also used to match the different impedances. In network technology, baluns are found in the Token Ring. The baluns used there are color coded: A red balun is for matching twisted-pair cable to coax (93/150 ohms) for 3270 terminals, the yellow one is also for coax (93 ohms) to twisted-pair cable with 150 ohms, and the green one is for matching on twinaxial cable to 150-ohm TP cable for 5520 terminals.
In audio technology, baluns are used in the transitions between the microphone cable or guitar cable to the electronic components such as mixer or amplifier, because the sensitive signals are routed through balanced cables, but the audio components often have unbalanced inputs.