What is the EL11 vacuum tube?

The EL11 is a pentode vacuum tube designed for power (se) applications. Side-contact Stahlroehre. Warm, rich..

What are the key specifications of the EL11?

Amplification factor μ ≈ 25, transconductance gm ≈ 9 mA/V, plate resistance rp ≈ 50.0 kΩ, max plate voltage 250 V, max plate dissipation 9 W, heater 6.3 V / 0.9 A.

Is the EL11 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the EL11 as Sought-after 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 EL11 sound like?

Side-contact Stahlroehre. Warm, rich.. 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.

EL11 Pentode Vacuum Tube

Small-signal pentode for low-noise voltage amplification

PentodeHeater 6.3 V · 0.9 A8-pin Side Contact Y8ATelefunken·Philips 1938

Plate dissipation: 9W
Max plate voltage: 250V
Max screen voltage: 275V
Max cathode current: 55mA
Transconductance: 9mA/V

EL11

Characteristics

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

HeaterIndirectly heated

Specifications of EL11 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.9 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of EL11 — Limiting values
Plate voltageVa max	250 V
Screen voltageVg2 max	275 V
Plate dissipationPa max	9 W
Screen dissipationPg2 max	1.2 W
Cathode currentIk max	55 mA
Grid resistorRg1 max	1 MΩ
Heater–cathode voltageVhk max	50 V

Mechanical

Specifications of EL11 — Mechanical
Base	8-pin Side Contact Y8A
Rarity	Sought-after
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of EL11 — Small signal
Transconductance	9 mA/V
Plate resistance	50 kΩ
Amplification factor	25

Capacitances

Specifications of EL11 — Capacitances
Input	10 pF
Grid–plate	0.8 pF
Output	8 pF

Charactereditorial reading, not a measurement

Specifications of EL11 — Character
Gain	25%
Power	23%
Drive	50%
Linearity	88%

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	Vg2	Vg1 / Rk	Ia	Ig2	Load	gm	μ	Source
Class A, single-endedpentode connection	250 V	250 V	-6 V	36 mA	4 mA	50 kΩ	9 mA/V	25	read on the sheet Philips · 1948 · 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, 2026

Manufacturer datasheets

3 manufacturer datasheets cross-checked for EL113 verified

EL11 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Telefunken·Philips
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The EL11 is a indirectly-heated pentode from Telefunken·Philips, introduced around 1938. It provides a gain factor (μ) of 25 with 50.0kΩ plate resistance. Commonly used in power (se) applications. Side-contact Stahlroehre. Warm, rich.

History

Introduced: 1938
Manufacturer: Telefunken·Philips
Era: Pre-War

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