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Deforest Spherical Audion
The filament of the Deforest Spherical Audion is a single strand of two loops. It is tungsten and would be bright like a lamp in operation. The grid is a zig zag of thick wire, and the plate is a rectangular. The filament connects to the screw base and the grid and plate connect at the top (see silk covered wires).

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Copyright 2003-2004 Howard Stone PhD.
stonevintageradio@gmail.com