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 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.

WE418A Tetrode Vacuum Tube

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

TetrodeHeater 6.3 V · 0.6 A9-pin MagnovalWestern Electric 1952

Plate dissipation: 8.5W
Max plate voltage: 250V
Transconductance: 26.5mA/V

WE418A

Characteristics

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

HeaterIndirectly heated

Specifications of WE418A — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.6 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of WE418A — Limiting values
Plate voltageVa max	250 V
Plate dissipationPa max	8.5 W

Mechanical

Specifications of WE418A — Mechanical
Base	9-pin Magnoval
Rarity	Collector
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of WE418A — Small signal
Transconductance	26.5 mA/V
Plate resistance	18 kΩ

Capacitances

Specifications of WE418A — Capacitances
Input	15 pF
Grid–plate	0.055 pF
Output	2.8 pF

Charactereditorial reading, not a measurement

Specifications of WE418A — Character
Gain	0%
Power	21%
Drive	82%
Linearity	75%

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

Typical operation

Conditions published by the manufacturers, one row per condition. Nothing is computed.

Typical operation
Setup	Va	Vg1 / Rk	Ia	gm	rp	Source
pentode connection, single-endedclass not stated · cathode bias	120 V	-1 V	47 mA	26.5 mA/V	18 kΩ	OCR, to be checked Western Electric · 1956 · p. 2 · transcript

Using this tube

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

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : Radiomuseum 418A (beam-power tetrode, 6.3V heater)

Manufacturer datasheets

1 manufacturer datasheets cross-checked for WE418A1 verified

WE418A DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Radiomuseum 418A (beam-power tetrode, 6.3V heater)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

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

Introduced: 1952
Manufacturer: Western Electric
Era: Golden Age

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