In many cases of observation the telephone conversations have to be monitored. With the PKI 2270 Telephone Transmitter (PCB) such tasks can easily be done. Due to its small size and unobtrusive appearance, this transmitter really is the champion in its class. The transmitter is supplied as a printed circuit board (PCB) only and is coated with a special protective lacquer which protects it against environmental conditions. This allows a fast and easy installation into every kind of analogue telephone set in which it looks like a standard component being completelyinconspicuous to the user. The installation inside the telephone set should be made in serial mode; both polarities are allowed. The PKI 2270 Telephone Transmitter (PCB) is only transmitting when a telephone conversation starts and therefore is non-detectable when the telephone is not in use. Another advantage is the independence from short-lived power supplies like batteries as the unit is continuously powered from the telephone line.