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JP-1A型示波极谱仪应用日益广泛,但在使用该机进行痕量测定并且电流倍率开关拨到高灵敏度档位时,扫描光点成为在Y轴方向的一条短线,而扫描线则变成一条宽带。这对低含量成分的测试精度造成很大影响,使检出下限受到限制,成为长期未能解决的一个问题。为了弄清干扰的来源,我们首先排除了仪器内部工作电流波纹系数过大这个因素。在此前提下用示波器对干扰信号进行了检查,发现扫描线宽带的形成乃是50周交流干扰信号同检测信号一同被垂直偏转放大器放大所致。尽管用普通示波器观察,在垂直偏转放大器的第一级的输入端(G13栅极)并没有发现明显的50周交流干扰信号,但是由于三级垂直偏转放大器的总放大倍数达3000～5000倍之多,因此,即使输入端存在极微弱的交流干扰也会使垂直偏转放大器的总输
JP-1A oscilloscope polarography is more and more widely used, but when using this machine for trace determination and current magnification switch to high-sensitivity gear, the scanning spot becomes a short line in the Y-axis direction, while the scanning line Become a broadband. This has a great impact on the testing accuracy of low-content components, which limits the lower detection limit and becomes a problem that has not been solved for a long time. In order to clarify the source of interference, we first rule out the internal operating current ripple factor is too large this factor. Under this premise, the oscilloscope was used to check the interference signal. It was found that the formation of the scan line width was caused by the fact that the AC interference signal was amplified by the vertical deflection amplifier together with the detection signal over 50 weeks. Although it is observed with a normal oscilloscope that no obvious 50-week AC interference signal is found at the input of the first stage of the vertical deflection amplifier (G13 gate), the total magnification of the three-stage vertical deflection amplifier is 3000-5000 times Therefore, even if there is very weak AC input interference will make vertical deflection amplifier total input