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研制了与已经开发的10kW中波功率放大器相适应的MOS-FET方式的调幅放大设备,因而完成了输出10kW的广播发射机系统。这种新调幅放大器的设计是基于高电压、低电流状态下工作的(高阻抗负载),是功率损耗增大时的最佳设计以及防止局部温升的理想散热设计等作为基本考虑方案,首先对MOS-FET的各种元件及参数进行了选择。其结果,输入、输出功率获得了良好的直线性,也能获得稳定的11.2kW以上功率输出。试制的调幅器单元,尺寸为230×530×700mm~3,重量21kg。由于强制风冷(风速10m/s),当发射机输出10kW时,MOS-FET的管壳表面温度升高9℃,LPF部件的线圈表温升高23℃。10kW发射机的综合特性是:总效率82%以上,失真度2%,信噪比52dB以上。
Developed the MOS-FET mode AM amplifying device that is compatible with the 10kW medium-frequency power amplifier that has been developed, thus completing a 10kW broadcast transmitter system. The design of this new AM amplifier is based on high-voltage, low-current operation (high impedance load), is the optimal design for increased power loss, and ideal thermal design to prevent local temperature rise as a basic consideration. First, Various components and parameters of the MOS-FET have been selected. As a result, input and output power to obtain a good linearity, but also to obtain a stable 11.2kW power output. Trial unit of the modulator, the size of 230 × 530 × 700mm ~ 3, weight 21kg. Due to forced air cooling (wind speed 10m / s), the surface temperature of the MOS-FET package increased by 9 ° C when the transmitter output was 10kW and the coil temperature of the LPF part increased by 23 ° C. The comprehensive characteristic of 10kW transmitter is: The total efficiency is above 82%, the degree of distortion is 2%, the signal to noise ratio is above 52dB.