Helium-filled half-wave rectifier. A 4-pin base with brass shell and ceramic insulator. Tipped S-shaped envelope. Maker's stamping on base reads: "Raytheon / Type B Patented / June 27, 1922 July 7, ...
A 4-pin plastic base, top contact, S-shaped envelope. Donor’s card reads: “Half wave mercury vapor rectifier made by the General Electric Company for the Radio Corporation of America in January 1929.
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