What is the RS241 vacuum tube?

The RS241 is a triode vacuum tube designed for power (se) applications. DHT transmitting triode. Wehrmacht heritage..

What is a RS241 substitute or equivalent?

Direct equivalents to the RS241 include 4C5. 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 RS241?

Amplification factor μ ≈ 17, transconductance gm ≈ 3.5 mA/V, plate resistance rp ≈ 5.0 kΩ, max plate voltage 400 V, max plate dissipation 15 W, heater 3.8 V / 0.6 A.

Is the RS241 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the RS241 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 RS241 sound like?

DHT transmitting triode. Wehrmacht heritage.. 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.

RS241 Triode Vacuum Tube

Also known as 4C5

Power triode delivering 15W for push-pull and SET designs

TriodeHeater 3.8 V · 0.6 A4-pin EuropeanTelefunken 1932

Plate dissipation: 15W
Max plate voltage: 400V
Transconductance: 3.5mA/V

RS241

Characteristics

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

HeaterDirectly heated

Specifications of RS241 — Heater
Heater voltageVh	3.8 V
Heater currentIh	0.6 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of RS241 — Limiting values
Plate voltageVa max	400 V
Plate dissipationPa max	15 W

Mechanical

Specifications of RS241 — Mechanical
Base	4-pin European
Rarity	Collector
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of RS241 — Small signal
Transconductance	3.5 mA/V
Plate resistance	5 kΩ
Amplification factor	17

Capacitances

Specifications of RS241 — Capacitances
Grid–cathode	6.5 pF
Grid–plate	9 pF
Plate–cathode	5 pF

Charactereditorial reading, not a measurement

Specifications of RS241 — Character
Gain	17%
Power	38%
Drive	95%
Linearity	92%

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

Generic triode power (se) stage

Hi-Fi stereo

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026

Manufacturer datasheets

1 manufacturer datasheets cross-checked for RS2411 verified

RS241 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

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

Context

The RS241 is a directly-heated triode from Telefunken, introduced around 1932. It provides a gain factor (μ) of 17 with 5000Ω plate resistance. Commonly used in power (se) applications. DHT transmitting triode. Wehrmacht heritage.

History

Introduced: 1932
Manufacturer: Telefunken
Era: Pre-War

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