(under subclass 199) Subject matter wherein the bias supply or isolating means is furnished to or for an input electrode of a vacuum tube amplifying device.
(1) Note. Input electrode refers to any electrode to which the electrical signal input is applied, usually the control grid physically next to the cathode and the cathode which is usually, also common to the input and output circuits of the amplifier, the anode being an output electrode. In grounded grid amplifiers the relationship of cathode and anode as described above is, of course, usually reversed.
(2) Note. Cathode self-biasing circuits where the bias is established by the flow of plate current through the cathode impedance are not classified herein.
SEE OR SEARCH THIS CLASS, SUBCLASS:
142, for cathode self-biasing circuits where the bias is established by the flow of plate current through the cathode impedance.
157+, 185+ and 192+, for impedances in the input electrode bias circuit involved in interstage, input, or output coupling, respectively.
