Helium-filled full-wave rectifier. A 4-pin base with brass shell and ceramic insulator. Tipped S-shaped envelope. Serial number "5144". Two ceramic-covered cylinders are set side by side on top the ...
Aluminum base shell with ceramic insulator, 4 short pins, top contact, T-shaped envelope. Stamped on envelope: "371B". Donor’s card reads: “Half-wave rectifier made by National Union for the US ...