论文部分内容阅读
问:电视机进行远距离接收效果很差,因此想在天线与电视机之间加装天线放大器以提高接收灵敏度,但又不了解这种放大器的具体结构。能否对此作一简单扼要的介绍。答:这里介绍一种宽频带天线放大器,它的电路和装配图见图1和图2。这是一个采用三级阻容耦合的级联放大器,使用频率为48～223兆赫,包括甚高频段12个电视频道和调频广播频率;增益为26分贝,不均匀度为±3分贝;最大输出电压为300毫伏;输入和输出阻抗都是75欧。电源为直流12伏,不论用干电池(1号干电池8节串联)或稳压电源均可。图1中,线圈L_1和L_3各用φ0.25毫米漆包线在1/8瓦、9.1千欧电阻上绕28匝;L_2用φ0.1毫米漆包线在5.1千欧电阻上绕40匝;L4用φ0.25毫米漆包
Q: Televisions are poorly received over long distances, so we wanted to install an antenna amplifier between the antenna and the TV to improve receiver sensitivity without knowing the exact structure of the amplifier. Can this be a brief introduction. A: Here to introduce a wideband antenna amplifier, the circuit and assembly drawings shown in Figure 1 and Figure 2. This is a cascaded amplifier with three RCA couplings, operating at 48 to 223 MHz, including 12 TV channels and FM radio at very high frequencies, a gain of 26 dB and an inhomogeneity of ± 3 dB, and a maximum output The voltage is 300 mV; the input and output impedances are 75 ohms. Power for the DC 12 volts, whether with a dry cell (No. 1 battery 8 series) or regulated power supply can be. Figure 1, the coil L_1 and L_3 each with φ0.25 mm enameled wire in the 1/8 watt, 9.1 kilohms resistance around 28 turns; L_2 φ0.1 millimeter enameled wire wound in the 5.1 kilohms 40; L4 with φ0 .25 mm enamel