| 摘要 |
<p>The remote inspection of seam welds in reactor vessels is improved through the utilization of a pulser network which is inductively isolated from the transducer circuit to which it applies an excitation signal. through the utilization of a step-up transformer, the pulser network may perform in conjunction with linear d.c. power supplies of lower voltage rating. The inductive coupling between circuits also serves to provide for the positive commutation off of switching devices such as SCRs employed for excitation signal triggering. To avoid ground path induced noise, a different ground path is employed for the pulser network as for the transducer circuit. The transducer circuit ground path is that associated with a manipulator and, for example, a reactor vessel itself. Thus, the transducers employed may come in contact with the surface of the vessel being inspected. In similar fashion, an inductive coupling is provided between the transducer circuit and a preamplfying receiver circuit. This same inductive coupling may be employed to enhance the impedance match between the FET-based amplification stage and the impedance defining components of the transducer circuit. <IMAGE></p> |
