6C3

6C3 is a designation used in Soviet and Russian valve (vacuum tube) nomenclature. In this system, the same code can refer to different tube variants produced over time for different circuit roles, so electrical characteristics may vary by variant. The term is most commonly associated with small-signal tubes used in radio and audio equipment from the mid-20th century.

The 6C3 family is linked to several variants, such as 6C3, 6C3P, and related suffix forms, produced by multiple manufacturers. Tubes in this lineage were employed as amplification elements, oscillators, or mixer devices within a range of equipment including consumer radios, military gear, and laboratory apparatus. While general purposes were similar, exact specifications such as heater configuration, filament voltage, plate current, and pinout differed between variants and production periods.

Because socket types and pin configurations vary, matching the correct 6C3 variant to a particular piece of equipment requires consulting original schematics or trusted reference catalogs. Availability today tends to be limited to vintage-electronics channels, surplus suppliers, and collector markets. Restoring equipment that uses 6C3 tubes typically involves verifying heater power, providing appropriate plate voltages, and ensuring compatible biasing to avoid tube damage.

Beyond the vacuum-tube context, the code 6C3 may appear in unrelated product codes or nomenclature, but the vacuum tube reference remains the most prominent and widely recognized use of the designation. The 6C3’s historical role in mid-20th‑century electronics continues to be of interest to enthusiasts and restorers of vintage gear.