Frequency Control of the Average Plate Current

Author: J.B. Hoag

An interesting case arises when both the plate and grid voltages of a thyratron are alternating. As indicated in Fig. 19 E, the plate current is not turned on until the grid voltage becomes less negative than the striking-potential indicated by the dotted lines.

Fig. 19 E. Frequency control of the plate current of a thyratron

For a low frequency on the grid, this results in current flow every positive half-cycle of the plate for a certain period of time, i.e., when the grid is passing through its positive half-cycle; followed by an interval of time, during most of the negative half-cycle of the grid voltage, when there is no plate current. When the frequency of the grid voltage is increased, the time intervals of current flow become longer, until, at a sufficiently high frequency, the current will flow during every positive half-cycle of the plate voltage.