Alkali vapor detector tubes

This paper describes unusual and very desirable results that are obtained on priming tungsten filament three-electrode vacuum tubes with an alloy of potassium and sodium when such tubes are used as detectors of radio frequency currents in receiving circuits. The method of preparing lite tubes and of introducing the alloy is described in some detail. Data obtained for these alkali vapor tubes are shown in the form of curves. They show the static characteristics of the tube, the operation characteristics rohen used as detectors, also the effect of filament temperature increase upon their performance. The results obtained when the tubes are used as detectors include — lower optimum plate voltage (5 to 10 volts), less critical adjustment of plate voltage, steady action, considerably greater sensitiveness to weak signals than for gas content lubes, and no distortion in detector action.