What is the 6KD6 vacuum tube?

The 6KD6 is a tetrode vacuum tube designed for sweep / power applications. Big sweep tube. Tougher than KT88..

What is a 6KD6 substitute or equivalent?

Direct equivalents to the 6KD6 include 6LF6, 6LB6. 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 6KD6?

Amplification factor μ ≈ 4, transconductance gm ≈ 14 mA/V, plate resistance rp ≈ 6.0 kΩ, max plate voltage 990 V, max plate dissipation 33 W, heater 6.3 V / 2.85 A.

Is the 6KD6 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6KD6 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 6KD6 sound like?

Big sweep tube. Tougher than KT88.. 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

←6KD6

← 6K6GT 6KX8 →Compare → 6LF6

6KD6 Tetrode Vacuum Tube

Tetrode6.3V / 2.85A12-pin Compactron

SourceRadiomuseum 6KD6 beam powerReviewed2026-05-29StatusDataModelCalcModelunder reviewPDF

Beam power tetrode rated at 33W for high-power output stages

Datasheet ↗

6KD6 — RCA·GE — tetrode vacuum tube — (1961)

6.0kΩ

14.0mA/V

40.0pF

0.8pF

16.00pF

GAIN4%

POWER83%

DRIVE94%

LINEARITY95%

SPECIFICATIONS

Heater6.3 V · 2.85 A

Max Plate Voltage990 V

Pa max33 W

Gain Factor4

gm14 mA/V

rp6.0 kΩ

Inter-electrode capacitances

Cgk40 pF

Cgp0.8 pF

Cpk16 pF

Pinout12-pin Compactron

Era1961

RarityCommon

HEATER6.3V / 2.85A

MAX PLATE990V / 33W

BASEcompactron

Source datasheets

2 manufacturer datasheets cross-checked for 6KD6

2 verified

EXECUTIVE SUMMARY

The 6KD6 is a indirectly-heated beam tetrode from RCA·GE, introduced around 1961. It provides a gain factor (μ) of 4 with 6000Ω plate resistance. Commonly used in sweep / power applications. Big sweep tube. Tougher than KT88.

APPLICATIONS

High-power output

Generic tetrode sweep / power stage

• PA/public address

VS 6LF6

Pd -18%Full comparison →

HISTORY

Introduced1961ManufacturerRCA·GE

Late Production

6KD6 Datasheet

Local mirror · PDF

↗

METRIX TESTER

Test this tube on a Metrix

SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.

SIMILAR TETRODES

View all →

12E1Power 1614Power (PP)1625Transmitting / Power 4Y100ROutput Power 4Y75ROutput Power 5881Power (PP)5AQ5Power 5V6Power