Telephone balance unit
|This article does not cite any sources. (January 2009)|
||It has been suggested that this article be merged into Telephone hybrid. (Discuss) Proposed since July 2012.|
A telephone balance unit (TBU) is a device to convert the unbalanced audio signal carried on a copper phone line to a balanced audio signal. It will also strip out any DC components (e.g. ringing signals or line power). The term telephone balance unit is commonly used in the UK. In the USA however, the term telephone hybrid is more commonly used.
In the USA these devices are more commonly called baluns by people using them. Radio amateurs use similar devices to match between coax and twinlead. TV stores sell them for matching twin lead from an external antenna to a coax input on a TV.
They are most commonly encountered in radio stations, where 'phone-ins' from members of the public need to be inserted into the broadcast chain and in news environments, where reporters 'phone in' a report.