Since 1984, one of the main goals of electronic specialists has been substituting high power vacuum tube with semiconductor devices. Because of high power and wide bandwidth, vacuum tubes are currently used whenever these two factors are needed. But introducing high power semiconductors is changing the history. By building separate power amplifiers and combining their outputs we can construct high power and high frequency systems such as broadcasting and high frequency systems such as broadcasting transmitters.
In this project a semiconductor- based HF transmitter with full carrier amplitude modulation has been designed and assembled. The carrier frequency is 11.34 MHz and the output power is about 500 watts. This output power is provided by combining the power produced by six class-D power modules. All amplifiers in this transmitter work in nonlinear (switching) mode so filtering the output of each block is necessary. The transmitter’s DC power supply is also a switched mode regulator.