The decoder has simply to be connected at the A.F. output (e.g. loudspeaker connection) of a VHF-radio. It is then possible to connect at the output of the decoder a stereo amplifier. Disconnectible, automatic switch-over mono-stereo when receiving the stereo signal. Stereo indication through LED. The decoder has simply to be connected at the A.F. output (e.g. loudspeaker connection) of a VHF-radio. It is then possible to connect at the output of the decoder a stereo amplifier. Disconnectible, automatic switch-over mono-stereo when receiving the st