(under subclass 238) Devices which have supporting and/or spacing structure for an indirectly heated cathode.
SEE OR SEARCH THIS CLASS, SUBCLASS:
263, and the subclasses specified in the notes thereto where the device is a discharge device which has a plurality of electrodes including an indirectly heated cathode supported by support structure within an envelope.
310, and the subclasses specified in the notes to the definition of that subclass for discharge devices which have an indirectly heated cathode.
337+, for the structure of indirectly heated cathodes, per se.
