Wartime parts shortages often meant that radio servicemen had to be creative, and that often meant tube substitution. If the replacement tube was not available, it was often possible to substitute one that was. The substitute often had similar or even identical electrical characteristics, but had a different size plug or pin configuration.

The June 1944 issue of Radio Craft, like many other radio magazines of the era, carried some pointers. The illustration shows common adapters. The base was made of a burnt out tube (perhaps the one being replaced), and the top was a new socket for the new tube. When tubes became available, the adapter could be removed and the original inserted in the socket.