(under subclass 199) Subject matter which may include the heater current supply for a filamentary cathode of a vacuum tube amplifying device not classified in any preceding subclass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
115, for amplifiers having unrectified A.C. power supplied to a filamentary cathode.
127, for control of emission of a cathode electrode.
201, for power supply bias means for cathode filaments in a plural stage amplifier heated by the anode current or by current from the anode supply source.
205, for similar subject matter for a filamentary cathode also involving power supply or bias means for an input
electrode. SEE OR SEARCH CLASS
315, Electric Lamp and Discharge Devices: Systems,
94+, for power supply or power supply circuit for cathode filament or cathode heater circuit with or without anode supply but not including grid biasing supply.
