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在人们日益追求高保真的趋势下,提高晶体管调幅收音机的抗干扰能力和放声音质已刻不容缓。要想达到高保真,除提高整机的静态失真和瞬态失真指标外,还要提高整机的频响和放声信噪比指标。目前世界上电台数量迅速增加,大功率化趋势有增无减,从而使中短波干扰日甚一日。用普通的晶体管超外差式调幅收音机接收夹在本地强信号群中的边远电台的弱信号时,常常会有明显的混信现象、背景杂声和差拍啸叫声,所以放声信噪比指标不但是一个抗机内噪声干扰的指标,而更重要的是一个抗机外噪声干扰的指标。为了解决抗干扰问题,普通调幅收音机一般都是将选择性放在主要矛盾,音质退居次要地位。目前质量较好的二级晶体管调幅收音机频响-5分贝仅在3.5千赫
Under the trend of people pursuing high fidelity, it is urgent to improve the anti-jamming capability and sound quality of transistor AM radio. In order to achieve high fidelity, in addition to improving the whole machine static distortion and transient distortion indicators, but also improve the machine’s frequency response and play signal to noise ratio indicators. At present, the number of radio stations in the world is rapidly increasing, and the trend of high-power consumption is on the increase. As a result, short-wave interference will soon start. When using a conventional super-heterodyne AM radio to receive a weak signal from a remote station sandwiched between local strong signal groups, there often will be mixed signals, background noises and beat whistling, so the signal-to-noise ratio Not only is an anti-aircraft noise interference indicators, but more important is an anti-machine noise interference indicators. In order to solve the anti-jamming problem, the ordinary AM radio generally places the selectivity on the main contradiction and the sound quality is relegated to a secondary position. At present, good quality two transistor AM radio frequency response -5 dB only at 3.5 kHz