6BK7

Small Signal Triode — Noval

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RCA

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Known Equivalents & Substitutes

6BK7A6BK7B

Similar Tubes (Not Drop-In Compatible)

4BZ8

Brans Vademecum cross-lists as equivalent — verify pinout and characteristics before substituting

6BC8

Similar HF twin triode for cascode circuits — different characteristics

6BQ7

Similar HF twin triode with same Noval base but different characteristics — not a drop-in

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Max Plate Voltage300V

Anode Dissipation (max)Max Plate Dissipation (per unit)2.7W

Heater-to-Cathode Voltage (max)Max Heater-Cathode Voltage200V

Typical Operating

Anode Voltage (typical)Plate Voltage (typical)150V

Notes

RCA datasheet (2-57) for the 6BK7-A revision. The 6BK7 and 6BK7A are electrically identical; the A suffix indicates a change in manufacturing process.
GE Essential Characteristics lists classification as 'High-Frequency Twin Triode' with base 9AJ, Rp=4700 ohms, Gm=8500 µmhos at Va=150 V. RCA datasheet gives Rp=4600 ohms, Gm=9300 µmhos — use RCA datasheet values.
Maximum plate voltage is 300 V. Maximum plate dissipation per unit is 2.7 W.
Peak heater-cathode voltage: 200 V max (both negative and positive). Under cutoff conditions in cascode circuits with direct-coupled drive, this may be as high as 300 V (DC component must not exceed 100 V).
Basing designation for bottom view is 9AJ (JETEC).

Pin Layout — Noval

1Plate (Unit 2)

2Grid (Unit 2)

3Cathode (Unit 2)

Socket-Compatible Tubes ⚠ Not electrically compatible

8CY7

References

https://frank.pocnet.net/sheets/137/6/6BK7.pdf
https://frank.pocnet.net/sheets/049/6/6BK7A.pdf

Anode Current

Plate Current

18mA

Anode ResistancePlate Resistance4,600Ω

TransconductanceTransconductance9.3mA/V

Amplification Factor (μ)Amplification Factor43—

Cathode Resistor (self-bias)Cathode Resistor56Ω

Capacitances

Grid-to-Plate CapacitanceGrid-to-Plate Capacitance (per unit)1.8pF

Grid-to-Cathode CapacitanceGrid-to-Cathode, Internal Shield and Heater Capacitance3pF

Input CapacitancePlate-to-Cathode, Internal Shield and Heater Capacitance (Unit 1)1pF

Output CapacitanceHeater-to-Cathode Capacitance2.8pF

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current0.45A

4Heater

5Heater

6Plate (Unit 1)

7Grid (Unit 1)

8Cathode (Unit 1)

9Internal Shield