transitron oscillator[′tran·sə‚trän ′äs·ə‚lād·ər]
a device for the generation of electrical oscillations by means of a multigrid electron tube (for example, a pentode) that, when operating, has a negative trans-conductance between the screen grid and the cathode. A transitron oscillator is excited when the absolute value of the transcon-ductance is equal to or more than the alternating-current resistance of the oscillatory circuit connected to the screen grid and the cathode. The frequencies of the oscillations generated in a transitron oscillator may range from a few hertz to several hundred megahertz. Since it has high frequency stability, the transitron oscillator has been used mainly as a master oscillator in radio transmitters and as a local oscillator in superheterodyne radio receivers. By the 1970’s, the transitron oscillator was superseded by semiconductor oscillators.