前言现代无线电接收设备中,通常采用超外差式电路,即输入信号由天线接收后,经高放、混频,尔后取出中频。其主要优点在于把多频率的信号变成固定频率,予以放大,可保证有较高的选择性,并满足一定的放大量。为此,放大固定频率的电路(简称中频放大器)就成为不可缺少的一部分。根据自己多年来的实践,体会到中频放大器的优劣会直接影响到接收机 Introduction Modern radio receiving equipment, usually super-heterodyne circuit, that is, the input signal received by the antenna, the high-Fang, mixing, and then remove the IF. The main advantage is that the multi-frequency signal into a fixed frequency, to be amplified, to ensure a higher selectivity, and to meet a certain amount of amplification. For this reason, amplifying a fixed frequency circuit (referred to as IF amplifier) ​​has become an indispensable part. According to their own practice over the years, I realized the pros and cons of IF amplifier will directly affect the receiver