What is the GI-7B vacuum tube?

The GI-7B (GI-7B / ГИ-7Б) is a triode vacuum tube designed for transmitting / hf-vhf applications. Coaxial microwave triode. Ham radio favorite..

What is a GI-7B substitute or equivalent?

Direct equivalents to the GI-7B include GI-70B. 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 GI-7B?

Amplification factor μ ≈ 30, transconductance gm ≈ 23 mA/V, plate resistance rp ≈ 1.3 kΩ, max plate voltage 2500 V, max plate dissipation 350 W, heater 12.6 V / 2.05 A.

Is the GI-7B still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the GI-7B 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 GI-7B sound like?

Coaxial microwave triode. Ham radio favorite.. 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.

GI-7B ГИ-7Б Triode Vacuum Tube

Also known as GI-70B

Power triode delivering 350W for push-pull and SET designs

TriodeHeater 12.6 V · 2.05 ACoaxial ringSvetlana 1960

Plate dissipation: 350W
Max plate voltage: 2500V
Transconductance: 23mA/V

GI-7B

Characteristics

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

HeaterIndirectly heated

Specifications of GI-7B — Heater
Heater voltageVh	12.6 V
Heater currentIh	2.05 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of GI-7B — Limiting values
Plate voltageVa max	2500 V
Plate dissipationPa max	350 W

Mechanical

Specifications of GI-7B — Mechanical
Base	Coaxial ring
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of GI-7B — Small signal
Transconductance	23 mA/V
Plate resistance	1.3 kΩ
Amplification factor	30

Capacitances

Specifications of GI-7B — Capacitances
Grid–cathode	11 pF
Grid–plate	4.5 pF
Plate–cathode	0.075 pF

Charactereditorial reading, not a measurement

Specifications of GI-7B — Character
Gain	30%
Power	100%
Drive	99%
Linearity	85%

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

SET output
Push-pull output
Headphone output

Generic triode transmitting / hf-vhf stage

Headphone ampPA/public address

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : G8WRB GI-7B datasheet

Manufacturer datasheets

1 manufacturer datasheets cross-checked for GI-7B / ГИ-7Б1 verified

GI-7B DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: G8WRB GI-7B datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The GI-7B is a indirectly-heated triode from Svetlana, introduced around 1960. It provides a gain factor (μ) of 30 with 1300Ω plate resistance. Commonly used in transmitting / hf-vhf applications. Coaxial microwave triode. Ham radio favorite.

History

Introduced: 1960
Manufacturer: Svetlana
Era: Late Production

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