What is the GMI-6 vacuum tube?

The GMI-6 (GMI-6 / ГМИ-6) is a tetrode vacuum tube designed for pulse modulator applications. Double beam tetrode. Pulse radar tube..

What is a GMI-6 substitute or equivalent?

Direct equivalents to the GMI-6 include No direct equivalent (Russian high-power transmitter beam tetrode). 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 GMI-6?

Max plate voltage 4000 V, max plate dissipation 15 W, heater 12.6 V / 1.1 A.

Is the GMI-6 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the GMI-6 as Rare 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 GMI-6 sound like?

Double beam tetrode. Pulse radar tube.. 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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GMI-6 GMI-6 / ГМИ-6 Tetrode Vacuum Tube

Dual tetrode12.6V / 1.1ABaseless glass

SourceSoviet-Tubes GMI-6 · pulse rating: 4kV pulse / 1kV CWReviewed2026-05-29StatusDataModelCalcModelunder reviewPDF

Beam power tetrode rated at 15W for high-power output stages

Datasheet ↗

GMI-6 / ГМИ-6 — Ulyanovsk — tetrode vacuum tube — (1958)

14.5pF

0.2pF

5.20pF

GAIN0%

POWER38%

DRIVE50%

LINEARITY75%

SPECIFICATIONS

Heater12.6 V · 1.1 A

Max Plate Voltage4000 V

Pa max15 W

Gain Factor—

gm—

rp—

Inter-electrode capacitances

Cgk14.5 pF

Cgp0.2 pF

Cpk5.2 pF

PinoutBaseless glass

Era1958

RarityRare

HEATER12.6V / 1.1A

MAX PLATE4000V / 15W

BASEspecial

SECTIONS2 (dual)

Source datasheets

1 manufacturer datasheets cross-checked for GMI-6 / ГМИ-6

1 verified

EXECUTIVE SUMMARY

The GMI-6 is a dual indirectly-heated beam tetrode from Ulyanovsk, introduced around 1958. Commonly used in pulse modulator applications. Double beam tetrode. Pulse radar tube.

APPLICATIONS

High-power outputPhase splitter

Generic tetrode pulse modulator stage

HISTORY

Introduced1958ManufacturerUlyanovsk

Golden Age

GMI-6 Datasheet

Local mirror · PDF

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METRIX TESTER

Test this tube on a Metrix

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

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