What is the 5Y3GT vacuum tube?

The 5Y3GT is a rectifier vacuum tube designed for rectifier applications. Classic sag. Blues tone..

What is a 5Y3GT substitute or equivalent?

Direct equivalents to the 5Y3GT include 5Y3G. 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.

Is the 5Y3GT still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 5Y3GT 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 5Y3GT sound like?

Classic sag. Blues tone.. 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.

5Y3GT Rectifier Vacuum Tube

Also known as 5Y3G

Full-wave rectifier for vacuum tube power supply designs

RectifierHeater 5 V · 2 AOctalRCA 1938

Max DC output current: 125mA
Peak inverse voltage: 1400V
Max RMS input per anode: 500V
Peak anode current: 400mA

5Y3GT

Characteristics

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

HeaterDirectly heated

Specifications of 5Y3GT — Heater
Heater voltageVh	5 V
Heater currentIh	2 A

Rectifier limitsDatasheet maximum ratings — not to be exceeded

Specifications of 5Y3GT — Rectifier limits
Max RMS input voltage per anode	500 V
Io max (DC output current)	125 mA
Peak inverse voltage (PIV)	1400 V
Peak anode current	400 mA
Tube voltage drop at Io	50 V at 125 mA
Max reservoir capacitor	32 µF
Min series resistance per anode	30 Ω

Mechanical

Specifications of 5Y3GT — Mechanical
Base	Octal
Rarity	Common
Pinout

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 supply rectification

Fender Champ PSUFender Deluxe PSU

Guitar amp

Featured in these amplifiers

Fender Champ (5F1) →

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : RCA datasheet · cap audit 2026-05-09

Manufacturer datasheets

5 manufacturer datasheets cross-checked for 5Y3GT5 verified

5Y3GT DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: RCA datasheet · cap audit 2026-05-09
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The 5Y3GT is a small full-wave directly-heated rectifier rated for about 125mA, with significant voltage sag under load. It is the stock rectifier in small to medium Fender tweed amplifiers including the Deluxe and Tremolux, where its substantial sag contributes directly to the coveted tweed compression and dynamic feel. The tube's limited current capability and high voltage drop (~60V) mean it is unsuitable for high-power applications, but in low-to-medium power amplifiers this becomes a feature rather than a limitation. It is inexpensive and widely available in both NOS and current production, making it the most accessible sag-contributing rectifier tube.

History

Introduced: 1938
Manufacturer: RCA
Era: Pre-War

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