What is the GK71 vacuum tube?

The GK71 (GK-71) is a pentode vacuum tube designed for transmitting applications. Russian transmitting pentode..

What are the key specifications of the GK71?

Amplification factor μ ≈ 5, transconductance gm ≈ 4 mA/V, max plate voltage 1500 V, max plate dissipation 125 W, heater 20 V / 3.1 A.

Is the GK71 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the GK71 as Moderate 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 GK71 sound like?

Russian transmitting pentode.. 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.

GK71 GK-71 Pentode Vacuum Tube

Power pentode delivering up to 125W in pentode, UL, or triode mode

PentodeHeater 20 V · 3.1 ASpecialRussian 1960

Plate dissipation: 125W
Max plate voltage: 1500V
Transconductance: 4mA/V

GK71

Characteristics

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

HeaterIndirectly heated

Specifications of GK71 — Heater
Heater voltageVh	20 V
Heater currentIh	3.1 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of GK71 — Limiting values
Plate voltageVa max	1500 V
Plate dissipationPa max	125 W

Mechanical

Specifications of GK71 — Mechanical
Base	Special
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of GK71 — Small signal
Transconductance	4 mA/V
Amplification factor	5

Capacitances

Specifications of GK71 — Capacitances
Input	18 pF
Grid–plate	0.15 pF
Output	17 pF

Charactereditorial reading, not a measurement

Specifications of GK71 — Character
Gain	5%
Power	100%
Drive	50%
Linearity	95%

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

Using this tube

Interactive loadline calculator not available for this tube yet — it needs calibrated Koren or Ayumi parameters.

Applications

Power output

Generic pentode transmitting stage

PA/public address

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : Soviet-Tubes ГК-71 datasheet · cap audit 2026-05-09

Manufacturer datasheets

1 manufacturer datasheets cross-checked for GK-711 verified

GK71 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Soviet-Tubes ГК-71 datasheet · cap audit 2026-05-09
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The GK71 is a indirectly-heated pentode from Russian, introduced around 1960. Commonly used in transmitting applications. Russian transmitting pentode.

History

Introduced: 1960
Manufacturer: Russian
Era: Late Production

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