(under subclass 111) Subject matter wherein the control of the electronic tube involves control of the cathode element.
(1) Note. Control of the cathode-anode circuit is not control of the cathode element.
(2) Note. A usual cathode element control is the control of cathode temperature.
SEE OR SEARCH CLASS
315, Electric Lamp and Discharge Devices: Systems,
94+, for miscellaneous systems for supplying heating current to the cathode or cathode heater of an electronic tube. The systems in Class 315, subclasses 94+ may include the circuit necessary to also supply the anode potential if the anode supply is included in combination with the supply of the cathode current. In such systems, the electronic tube may be either a vacuum tube or a gas or vapor tube. However, if the system includes the supply of control current or potential to the discharge control means, then only the systems limited to having an electronic tube of the gas or vapor type are included, and such other systems will be found in Class 250, Radiant Energy, or in one of the classes or subclasses specified in the notes to the definition of that subclass.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, appropriate subclasses for miscellaneous electron tube systems which include means for controlling the cathode element. See the reference to Class 315, above.
