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在普通的超外差收音机中已广泛地使用了调谐指示管,在某些电子仪器中(如精密频率计、电位器杂音检查仪等),也使用了调谐指示管作为可见指示.在这些使用场合中,有时,使用者会感到调谐指示管的指示灵敏度不够.例如,在使用超外差收音机接收短波电台时,调谐指示管往往不起作用.因此,有必要设法提高调谐指示管的灵敏度.在某些资料中曾对提高调谐指示管指示灵敏度问题有过介绍,图1所示电路即是其中之一.然而这些电路的效果均不十分满意.这里
Tuning indicator tubes have been used extensively in conventional superheterodyne radios and tuning indicators have also been used as visual indicators in some electronic devices (eg, precision frequency counters, potentiometer noise testers, etc.) Occasionally, users may find that the tuning indicator tube is not sensitive enough, for example, when using a superheterodyne receiver to receive shortwave radios, the tuning indicator tube often does not work, so it is necessary to try to increase the sensitivity of the tuning indicator tube. In some cases, there was an introduction to the problem of increasing the sensitivity of the tuning indication tube. The circuit shown in Figure 1 is one of them, however, the effects of these circuits are not satisfactory.