Definition of "heptode" []

• A compound thermionic valve containing a triode and tetrode; was used in superheterodyne radio receivers (noun)

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• "Graphical Symbol in full simplified diode, indirectly heated duodiode, indirectly heated or triode, indirectly heated or duotriode with separated cathodes, indirectly heated, heating filament with central tapping, internal screening of the system tetrode pentode, suppressor grid connected with cathode triode - pentode triode - heptode (according to the circuit, the systems may be drawn left-and-right reversed) 1.10."