传统的超外差收音机制作工艺精美、使于携带,在上世纪60年代至本世纪初成为千家万户普遍使用的小家电。如今电脑网络技术的发展使收音机变得有些清闲,我们不妨请闲暇的收音机来充当演示实验的教具。找一台老式分立元件的超外差收音机,将其改制成发射机,它与收音机配合起来可演示电磁波的发射与接收。一、基本原理超外差机的电路中都含有本机振荡电路,且本机振荡频率高于外来电台的频率,其差值为465kHz。中波段收音机频率范围在535kHz～1605kHz之间,因此本机振荡频率则为1000kHz～2070kHz,可见本机 Traditional superheterodyne radio production process beautiful, so that the portable, in the 60s of last century to the beginning of this century as a universal household appliances to millions of households. Today, the development of computer network technology to make the radio become a bit leisure, we may wish to spare the radio to act as teaching aids experiment. Look for a super-heterodyne radio with an old discrete component that is converted into a transmitter that, in conjunction with a radio, can demonstrate the transmission and reception of electromagnetic waves. First, the basic principles Superheterodyne circuit contains the local oscillator circuit, and the local oscillator frequency is higher than the frequency of external radio, the difference is 465kHz. The mid-band radio frequency range between 535kHz ~ 1605kHz, so the local oscillation frequency is 1000kHz ~ 2070kHz, we can see the machine