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受《电子制作》1997年11期的“不用仪器调中周”的启发,觉得此法可行,但操作繁琐,于是自制小仪器,能够准确校准38MHz中周,效果良好,简单实用。 1.工作原理:参阅附图。V1、L及与外围元件组成电容三点式振荡器,振荡频率为38MHz,V2对振荡信号进行放大,被测中周接于A、B两点,是V2的负载,D1、D2组成倍压检波,由电压表指示输出。 2.元件选择:(1)L用38MHz中周TLI151757去掉内附电容即可;(2)V1、V2用高频管3DG142;(3)电压表选用2.5V直流表头;(4)电源用9V层叠电池;(5)DW选用6V的2DW234。
Inspired by “Electronic Manufacturing”, 1997, “No Instrument Tune Week”, I think this method is feasible, but the operation is cumbersome. Therefore, the small homemade instrument can accurately calibrate 38MHz Zhouzhong, with good effect and simple and practical. 1. How it works: see the photo V1, L and the external components with three-point capacitance oscillator, the oscillation frequency of 38MHz, V2 on the oscillation signal amplification, measured in the next A, B two points, is the load of V2, D1, D2 doubling voltage detection, Indicated by the voltmeter output. (2) V1, V2 with high frequency tube 3DG142; (3) voltmeter selection of 2.5V DC meter; (4) power supply with 9V laminated battery; (5) DW selected 6V 2DW234.