The Russian 6P3S (6П3С) is an output beam tetrode designed for power amplification in single-ended and push-pull low-frequency amplifier stages. It is the Soviet equivalent of the 6L6GT and 6L6, and was manufactured by the famous FOTON plant for military equipment. The tube is a New Old Stock (NOS) item, never used.

Key Features & Specifications

• Name: 6P3S / 6П3С
• Type: output beam tetrode
• Application: LF power amplification, RF generation in transmitters
• Cathode type: oxide, indirect heating
• Envelope: glass
• Base: octal, 6 pins with key
• Filament voltage: 6.3 V
• Filament current: 900 mA ± 60 mA
• Anode voltage: 250 V (nominal); 400 V maximum
• Grid 2 voltage: 250 V (nominal); 300 V maximum
• Grid 1 voltage: −14 V (nominal)
• Anode current: 72 mA ± 14 mA
• Grid 2 current: ≤ 8 mA
• Transconductance: 6 mA/V ± 0.8 mA/V
• Internal resistance: 22.5 kΩ
• Amplification factor: 13.5
• Output power: 5.4 W (at 9.8 V grid drive, 2.5 kΩ load)
• Max anode dissipation: 20.5 W
• Max grid 2 dissipation: 2.75 W
• Interelectrode capacitances: input 11 pF, output 8.2 pF, transfer ≤ 1 pF
• Service life: ≥ 500 hours

Applications & Compatibility

• Primary use: output stage of low-frequency amplifiers in radio receivers, PA systems, and military equipment.
• Audio use: a direct replacement for the 6L6GT and 6L6 in guitar amplifiers, hi-fi amplifiers, and vintage radio restoration.
• RF use: also suitable as an RF generator in transmitters and other equipment, operating at frequencies up to several MHz.
• Equivalents: 6L6, 6L6GT, 6L6G, 5881; close analogues include 6L50, EL35, EL39, 1622, 5932, 7581A.

Condition

• Status: NEW, NOS (New Old Stock). Never used before.
• Origin: Made in the USSR by the FOTON plant.

Why Choose This Tube?

The 6P3S from the FOTON plant delivers the classic 6L6 tone that has defined generations of guitar and hi-fi amplifiers, with the rugged construction of Soviet military production. Its octal base and glass envelope make it easy to work with in restoration projects, while its electrical characteristics allow it to substitute directly for the 6L6GT and 6L6 in most circuits. The FOTON plant was a major supplier of military-grade tubes, and this NOS example reflects that heritage in its consistent performance and durability. Whether you are recapping a vintage radio, voicing a guitar amp, or building a new single-ended design, the 6P3S offers authentic 6L6-family sound and dependable Soviet engineering in a familiar octal package.