The ZETFON 300/310 is an electronic sound transmitter. It consists of the ZETFON (sound emitter) itself mounted on the mast and a control and amplifier unit for wheelhouse installation. The control and amplifier unit contains all electronic components including the heavy transformer. This way heavy weight on the mast is avoided and vital components are within easy reach. The ZETFON is an economic alternative to air whistles on vessels without air compressor.