What is the 6BQ7A vacuum tube?

The 6BQ7A is a triode vacuum tube designed for rf / preamp applications. Cascode RF dual triode..

What are the key specifications of the 6BQ7A?

Amplification factor μ ≈ 38, transconductance gm ≈ 6.4 mA/V, plate resistance rp ≈ 5.9 kΩ, max plate voltage 250 V, max plate dissipation 2 W, heater 6.3 V / 0.4 A.

Is the 6BQ7A still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6BQ7A 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 6BQ7A sound like?

Cascode RF dual triode.. 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.

6BQ7A Triode Vacuum Tube

Medium-gain triode for driver and line stage applications

Dual triodeHeater 6.3 V · 0.4 A9-pin Noval2 sectionsRCA 1955

Plate dissipation: 2W
Max plate voltage: 250V
Amplification factor: 38
Transconductance: 6.4mA/V
Plate resistance: 5.9kΩ

6BQ7A

Characteristics

Datasheet values, once each. Every value cites its sheet.

HeaterIndirectly heated

Specifications of 6BQ7A — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.4 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6BQ7A — Limiting values
Plate voltageVa max	250 V
Plate dissipationPa max	2 W

Mechanical

Specifications of 6BQ7A — Mechanical
Base	9-pin Noval
Rarity	Common
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6BQ7A — Small signal
Transconductance	6.4 mA/V
Plate resistance	5.9 kΩ
Amplification factor	38

Capacitances

Specifications of 6BQ7A — Capacitances
Grid–cathode	2.85 pF
Grid–plate	1.15 pF
Plate–cathode	1.35 pF

Charactereditorial reading, not a measurement

Specifications of 6BQ7A — Character
Gain	38%
Power	5%
Drive	94%
Linearity	81%

datasheet cited · model or editorial reading · catalogue value, no citation attached yet · nothing invented

Typical operation

Canonical operating pointModel

B+: 200 V
Load: 5 kΩ
Va: 120 V
Ia: 1.76 mA
Vg: -3 V
Pd: 0.21 W
Gain: 19.6 dB

At Q: Norman Koren
μ: 34.2
gm: 2.3 mA/V
rp: 14.9 kΩ

Design a stage →

Using this tube

Applications

Voltage amplifier
Phase splitter

Generic triode rf / preamp stage

Hi-Fi stereoHeadphone amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : audit-us_a (CLEAN — matches canonical datasheet)Active model : Norman Koren

Manufacturer datasheets

5 manufacturer datasheets cross-checked for 6BQ7A5 verified

6BQ7A DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: audit-us_a (CLEAN — matches canonical datasheet)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Norman Koren

Context

The 6BQ7A is a dual indirectly-heated triode from RCA, introduced around 1955. It provides a gain factor (μ) of 38 with 5900Ω plate resistance. Commonly used in rf / preamp applications. Cascode RF dual triode.

History

Introduced: 1955
Manufacturer: RCA
Era: Golden Age

METRIX TESTER