[mikethedruid]

Loctal vs octal. They may have been marketed as "pin for pin compatible," but that actually meant you could replace the octal socket with a loctal socket easily, or buy an adapter. the loctal tubes never were meant to actually work directly in octal sockets, any fool who ever tried it found out immediately that it didn't work. As time went on, by the 1960s, loctal tubes were becoming difficult to find. I know this because I was already collecting antique radios by then, and didn't bother with the later Philcos at the time because they used loctals, or any other radio that used them. RCA and Crosley never seem to have made this mistake.