Thyratron Rectifiers

Author: J.B. Hoag

As we have seen in a previous section of this chapter, the plate current through a thyratron flows only during the positive half-cycles of the plate voltage. Hence a thyratron may be used as a rectifier. Furthermore, it is possible to change the output current of such a rectifier by the phase-control method just described. A circuit of this type is shown in Fig. 19 L.

Fig. 19 L. Phase controlled thyratron rectifier circuit

Two-electrode gas-filled tubes may be used as rectifiers whenever larger current outputs are desired than can be passed by vacuum tubes. In using hot-cathode gas-filled tubes, it must be remembered that the cathode is to be hot before the high voltage is applied and is to be kept hot until the plate voltage has been removed. Otherwise, the operating life of the tube will be reduced by disintegration of the filament under positive ion bombardment. It must also be recalled that with vacuum tubes the internal resistance is sufficiently great to keep the current to a safe value, whereas, with gas-filled tubes, the current flow is determined by the applied voltage and the external resistance.