What is the 6K6GT vacuum tube?

The 6K6GT is a pentode vacuum tube designed for power (se) applications. Charming low-power SE..

What is a 6K6GT substitute or equivalent?

Direct equivalents to the 6K6GT include 41. 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 6K6GT?

Amplification factor μ ≈ 7, transconductance gm ≈ 2.3 mA/V, plate resistance rp ≈ 90.0 kΩ, max plate voltage 315 V, max plate dissipation 8.5 W, heater 6.3 V / 0.4 A.

Is the 6K6GT still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6K6GT 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 6K6GT sound like?

Charming low-power SE.. 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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6K6GT Pentode Vacuum Tube

Pentode6.3V / 0.4AOctalSPICE

SourceRCAReviewed2026-05-29StatusDataModelCalcModelKoren pentodePDF

Small-signal pentode for low-noise voltage amplification

Datasheet ↗SPICE

6K6GT — RCA — pentode vacuum tube — (1937)

90.0kΩ

2.3mA/V

5.5pF

0.5pF

6.00pF

GAIN7%

POWER21%

DRIVE10%

LINEARITY95%

SPECIFICATIONS

Heater6.3 V · 0.4 A

Max Plate Voltage315 V

Pa max8.5 W

Gain Factor7

gm2.3 mA/V

rp90.0 kΩ

Inter-electrode capacitances

Cgk5.5 pF

Cgp0.5 pF

Cpk6 pF

PinoutOctal

Era1937

RarityCommon

HEATER6.3V / 0.4A

MAX PLATE315V / 8.5W

BASEoctal

Source datasheets

4 manufacturer datasheets cross-checked for 6K6GT

4 verified

EXECUTIVE SUMMARY

The 6K6GT is a indirectly-heated pentode from RCA, introduced around 1937. It provides a gain factor (μ) of 7 with 90.0kΩ plate resistance. Commonly used in power (se) applications. Charming low-power SE.

HISTORY

Introduced1937ManufacturerRCA

Pre-War

6K6GT Datasheet

Local mirror · PDF

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METRIX TESTER

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