What is the 813 vacuum tube?

The 813 is a pentode vacuum tube designed for transmitting applications. Beam tetrode giant. Deep controlled bass in triode..

What is a 813 substitute or equivalent?

Direct equivalents to the 813 include VT-144. 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 813?

Amplification factor μ ≈ 8, transconductance gm ≈ 3.75 mA/V, max plate voltage 2500 V, max plate dissipation 125 W, heater 10 V / 5 A.

Is the 813 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 813 as Moderate 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 813 sound like?

Beam tetrode giant. Deep controlled bass in triode.. 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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813 Pentode Vacuum Tube

Pentode10V / 5ASpecial

SourceRCA 813 datasheet (beam tetrode classification) · cap audit 2026-05-09Reviewed2026-05-29StatusDataModelCalcModelunder reviewPDF

Power pentode delivering up to 125W in pentode, UL, or triode mode

Datasheet ↗

813 — RCA·Amperex — pentode vacuum tube — (1938)

3.8mA/V

16.3pF

0.3pF

14.00pF

GAIN8%

POWER100%

DRIVE50%

LINEARITY95%

SPECIFICATIONS

Heater10 V · 5 A

Max Plate Voltage2500 V

Pa max125 W

Gain Factor8

gm3.75 mA/V

rp—

Inter-electrode capacitances

Cgk16.3 pF

Cgp0.25 pF

Cpk14 pF

PinoutSpecial

Era1938

RarityModerate

HEATER10V / 5A

MAX PLATE2500V / 125W

BASEspecial

Source datasheets

2 manufacturer datasheets cross-checked for 813

2 verified

EXECUTIVE SUMMARY

The 813 is a directly-heated pentode from RCA·Amperex, introduced around 1938. Commonly used in transmitting applications. Beam tetrode giant. Deep controlled bass in triode.

APPLICATIONS

Power output

Generic pentode transmitting stage

• PA/public address

HISTORY

Introduced1938ManufacturerRCA·Amperex

Pre-War

813 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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