论文部分内容阅读
超外差式接收机为了简化调谐手续,节省调谐时间,和提高短波电台的调谐准确度往往采用单一旋钮控制的高频波段展阔回路及其统调的外差振荡回路。这两种回路的基本原理是一致的,它们都牵涉到如何利用固定的串并联电容器来缩短调谐回路的波段复盖,从而获得准确跟踪的统一调谐的波段展阔电路。这一类型电路的结构,原理和计算方法将分别在下列各节计论之。
In order to simplify the tuning procedure, save the tuning time and improve the tuning accuracy of the shortwave radio, the superheterodyne receiver often adopts a single knob-controlled high-frequency band expander loop and its coordinated heterodyne oscillation circuit. The basic principle of these two circuits is the same, all of them involve how to use a fixed series-shunt capacitor to shorten the band coverage of the tuning loop so as to obtain a uniformly tracked and uniformly tuned band broadening circuit. This type of circuit structure, principles and calculation methods will be discussed in the following sections.