Nonode

File:Fm ennode det.svg

A nonode is a type of thermionic valve that has nine active electrodes. The term most commonly applies to a seven-grid vacuum tube, also sometimes called an enneode. An example was the EQ80/UQ80, which was used as an FM quadrature detector.{{cite news |last1=Schindler |first1=Patrik |title=EQ80 Enneode |url=https://frank.pocnet.net/sheets/046/e/EQ80.pdf |work=Electron Tube Data sheets |pages=413–422}} It was developed during the introduction of TV and FM radio and delivered an output voltage large enough to directly drive an end pentode while still allowing for some negative feedback. As most of the grids were tied together, even an 8-pin Rimlock base was sufficient in the case of the EQ40.{{citation needed|date=November 2024}}