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“美多牌”28A型晶体管携带式收音机,是上海无线电三厂1963年的新产品.本机电路系中短波超外差式,采用独立振荡混频电路,中频放大用二级,采用二极管检波兼自动增益控制,通过二级低频放大再送至末级推挽乙类放大器以完成整机从高频信号输入以至功率输出,为了改进整机的低频效果,接入负回授电路以减小失真系数.全
“United States and more cards ” 28A transistor portable radio, Shanghai Radio Factory in 1963. The local circuit in the short-wave super-heterodyne type, using an independent oscillator mixer circuit, intermediate frequency amplification with two, using Diode detection and automatic gain control, through the two low-frequency amplification and then sent to the final stage push-pull B amplifier to complete the machine from high-frequency signal input and power output, in order to improve the low frequency effect of the machine, access to the negative feedback circuit to reduce Small distortion factor