What is the WE418A vacuum tube?

The WE418A is a tetrode vacuum tube designed for driver / power applications. High-Gm frame-grid tetrode. Superb triode-strapped..

What is a WE418A substitute or equivalent?

Direct equivalents to the WE418A include None direct. 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 WE418A?

Transconductance gm ≈ 26.5 mA/V, plate resistance rp ≈ 18.0 kΩ, max plate voltage 250 V, max plate dissipation 8.5 W, heater 6.3 V / 0.6 A.

Is the WE418A still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the WE418A as Collector 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 WE418A sound like?

High-Gm frame-grid tetrode. Superb triode-strapped.. 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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WE418A Tetrode Vacuum Tube

Tetrode6.3V / 0.6A9-pin Magnoval

SourceRadiomuseum 418A (beam-power tetrode, 6.3V heater)Reviewed2026-05-29StatusDataModelCalcModelunder reviewPDF

Beam power tetrode rated at 8.5W for high-power output stages

Datasheet ↗

WE418A — Western Electric — tetrode vacuum tube — (1952)

18.0kΩ

26.5mA/V

15.0pF

0.1pF

2.80pF

GAIN0%

POWER21%

DRIVE82%

LINEARITY75%

SPECIFICATIONS

Heater6.3 V · 0.6 A

Max Plate Voltage250 V

Pa max8.5 W

Gain Factor—

gm26.5 mA/V

rp18.0 kΩ

Inter-electrode capacitances

Cgk15 pF

Cgp0.055 pF

Cpk2.8 pF

Pinout9-pin Magnoval

Era1952

RarityCollector

HEATER6.3V / 0.6A

MAX PLATE250V / 8.5W

BASEmagnoval

Source datasheets

1 manufacturer datasheets cross-checked for WE418A

1 verified

EXECUTIVE SUMMARY

The WE418A is a indirectly-heated beam tetrode from Western Electric, introduced around 1952. Commonly used in driver / power applications. High-Gm frame-grid tetrode. Superb triode-strapped.

HISTORY

Introduced1952ManufacturerWestern Electric

Golden Age

WE418A 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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