Tube socket

Tube sockets are electrical sockets into which vacuum tubes (also known as valves) can be plugged, holding them in place and providing terminals, which can be soldered into the circuit, for each of the pins. Sockets are designed to allow tubes to be plugged in in only one orientation. They were used in all tube electronic equipment to allow tubes, which failed relatively frequently, to be quickly tested and replaced. In the day of tube radio and television it was common in the US for local drug stores to have vacuum tube testers, and sell replacement tubes.