What is the 6BQ6GTB vacuum tube?

The 6BQ6GTB is a tetrode vacuum tube designed for power applications. TV sweep repurposed..

What is a 6BQ6GTB substitute or equivalent?

Direct equivalents to the 6BQ6GTB include 6CU6. These share the same pinout and operating envelope, so they can usually be swapped without circuit changes — though batch-to-batch variations between manufacturers (NOS vs current production) may shift the sonic character noticeably.

What are the key specifications of the 6BQ6GTB?

Amplification factor μ ≈ 4, transconductance gm ≈ 5.9 mA/V, plate resistance rp ≈ 14.5 kΩ, max plate voltage 600 V, max plate dissipation 11 W, heater 6.3 V / 1.2 A.

Is the 6BQ6GTB still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6BQ6GTB as Common availability. NOS (new-old-stock) examples from RCA, Mullard, Tung-Sol, GE, Sylvania and Telefunken trade among collectors; modern production where it exists comes mostly from JJ Electronic, Electro-Harmonix, Tung-Sol (New Sensor), Genalex, and a handful of small-batch makers.

What does the 6BQ6GTB sound like?

TV sweep repurposed.. Sonic character also depends heavily on the circuit operating point, the surrounding tubes in the stage, and the output transformer when present — use the interactive loadline calculator on this page to explore the trade-offs.

By Jean-Michel Falligan Devergne · Reviewed May 29, 2026

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6BQ6GTB Tetrode Vacuum Tube

Tetrode6.3V / 1.2AOctalSPICE

Sourceaudit-us_a (CLEAN — matches canonical datasheet)Reviewed2026-05-29StatusDataModelCalcModelKoren pentodePDF

Beam power tetrode rated at 11W for high-power output stages

Datasheet ↗SPICE

6BQ6GTB — RCA — tetrode vacuum tube — (1955)

14.5kΩ

5.9mA/V

15.0pF

0.6pF

7.00pF

GAIN4%

POWER28%

DRIVE86%

LINEARITY95%

SPECIFICATIONS

Heater6.3 V · 1.2 A

Max Plate Voltage600 V

Pa max11 W

Gain Factor4

gm5.9 mA/V

rp14.5 kΩ

Inter-electrode capacitances

Cgk15 pF

Cgp0.6 pF

Cpk7 pF

PinoutOctal

Era1955

RarityCommon

HEATER6.3V / 1.2A

MAX PLATE600V / 11W

BASEoctal

Source datasheets

3 manufacturer datasheets cross-checked for 6BQ6GTB

3 verified

EXECUTIVE SUMMARY

The 6BQ6GTB is a indirectly-heated beam tetrode from RCA, introduced around 1955. It provides a gain factor (μ) of 4 with 14.5kΩ plate resistance. Commonly used in power applications. TV sweep repurposed.

HISTORY

Introduced1955ManufacturerRCA

Golden Age

6BQ6GTB Datasheet

Local mirror · PDF

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METRIX TESTER

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