The 6SC7 is a high-mu dual triode vacuum tube designed for high-gain audio voltage amplifiers and phase inverter circuits in radio receivers. Units are available in both new old stock (NOS) and tested used conditions. Manufactured by companies including RCA, Sylvania, GE, and Ken-Rad, these tubes feature a 6.3V filament rating, common-cathode construction, and an octal base design in a metal envelope. Used for servicing vintage radio chassis, early phono preamplifiers, and guitar amplifiers requiring high voltage gain.