6B4G

Power Triode — DHT — Octal

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Tung-Sol

↗ r-type.org ↗ TDSL ↗ Radiomuseum

Known Equivalents & Substitutes

6S4S

Similar Tubes (Not Drop-In Compatible)

2A3

Electrically identical power triode (mu=4.2, 3.5W SE) but on UX4 base with 2.5V filament — not pin-compatible

6A3

Same electrical characteristics and 6.3V filament but on UX4 base — not pin-compatible with Octal 6B4G

AC042

European equivalent listed in Brans Vademecum — same table IIIb grouping

ZA3W

Equivalent listed in Brans Vademecum — same table IIIb grouping

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Max. Plate Voltage325V

Max Grid ResistorMax. Grid Resistor (self bias)0.5MΩ

Max Grid ResistorMax. Grid Resistor (fixed bias)0.05MΩ

Typical Operating

Anode Voltage (typical)Plate Voltage250V

Notes

The 6B4G is essentially a 2A3 re-based on an Octal socket with a 6.3V/1.0A filament instead of the 2A3's 2.5V/2.5A filament.
Ratings and characteristics are similar to the 2A3 and 6A3: mu=4.2, gm=5250 umhos, ra=800 ohm at Va=250V.
The 6S4S (6C4C) is the Soviet-era Russian equivalent (russian_equivalents reference).
Brans Vademecum groups 6B4G with 2A3, 2A3W, 6A3, AC042, and ZA3W in table IIIb (directly heated power triodes).
Pin 1 is no connection on the Octal base. Filament connections are on pins 2 and 7. Plate on pin 3, grid on pin 5.

Pin Layout — Octal

1No Connection

2Filament

3Plate

References

https://frank.pocnet.net/sheets/127/6/6B4G.pdf

Grid 1 Bias VoltageGrid Voltage-45V

Anode CurrentPlate Current60mA

Anode ResistancePlate Resistance800Ω

TransconductanceTransconductance5.25mA/V

Amplification Factor (μ)Amplification Factor4.2—

Output

Output PowerPower Output (SE Class A1)3.2W

Load ImpedanceLoad Resistance (SE Class A1)2,500Ω

Capacitances

Grid-to-Plate CapacitanceGrid-to-Plate Capacitance16pF

Grid-to-Cathode CapacitanceGrid-to-Filament Capacitance7pF

Anode-to-Cathode CapacitancePlate-to-Filament Capacitance5pF

Heater

Heater VoltageFilament Voltage6.3V

Heater CurrentFilament Current1A

No Connection

5Grid

6No Connection

7Filament

8No Connection