Radio transmitter withAM grid modulation - has preamplifier synchronised with modulation signal to raise efficiency of transmission

摘要

The radio transmitter is used for SW, MW and LW outputs and has AM grid modulation. It has a high efficiency independent of the modulation factor and it has low nonlinear distortion even at large modulation factors. The modulator controls the main power amplifier and is also connected via a diode to the sync. control circuit that controls the preamplifier. The sync. control circuit contains a transistor in series with the cathode circuit of the preamplifier (2) and connected by its base to the rectifier. The output amplitude of the preamplifier which is used to drive the grid of the power stage (3) is therefore synchronised with the modulation signal from the modulator (6).