A method is provided for controlling a load signal of a signal transmitter in a data system for sending data in a low voltage network in order to keep an input signal voltage constant. The load signal is supplied through a coupling unit that provides signal coupling the network. The data transmission system also includes a signal amplifier, a signal filter and a source of signal amplifier operating voltage. The signal amplifier includes a signal clipper or a function for clipping the output signal of the signal amplifier and/or for clipping the input signal amplifier. The clipping is dependent on the output voltage of the signal to be sent to the network or on the output current from signal amplifier.