New-Old-Stock (NOS) tube.

The 6679 is a miniature high-mu twin triode suitable for use as a grounded-grid amplifier or as a frequency converter at frequencies below approximately 300 megacycles. Its electrical characteristics are essentially equivalent to those of the 12AT7.

Intended specifically for use in mobile communications equipment, the 6679 may be operated without serious degradation under normal variations in supply voltage as encountered with automotive electrical systems. Also consistent with the requirements of this equipment, the tube is capable of withstanding appreciable on-of cycling.