New-Old-Stock (NOS) tube.

The 6EA8 is a miniature tube which contains a sharp-cutoff pentode and a triode in one envelope. Each section has a separate cathode and is electrically independent. The tube is primarily intended for service as a combined triode oscillator and pentode mixer in television receivers. Incorporation of a controlled heater warm-up characteristic makes the tube especially suited for use in television receivers that employ series-connected heaters.