Filament Supply for Radio Receiver from Rectified 25-Kilocycle Current

A method of generating, rectifying, and filtering 25-kc current for supplying filament power to ordinary d-c amplifier tubes in radio receivers is described. The oscillator used to generate the 25-kc current was of a special design and contained one or more UX-210 power tubes. The dry contact type rectifier unit was used, and cathode-ray oscillograms of the output current were taken. Operating tests were made of the performance of radio receivers.