What is the VT-103 vacuum tube?

The VT-103 is a tetrode vacuum tube designed for preamp applications. Military designation..

What is a VT-103 substitute or equivalent?

Direct equivalents to the VT-103 include 6SQ7. 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 VT-103?

Amplification factor μ ≈ 100, transconductance gm ≈ 6 mA/V, plate resistance rp ≈ 91.0 kΩ, max plate voltage 750 V, max plate dissipation 30 W, heater 6.3 V / 0.3 A.

Is the VT-103 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the VT-103 as Rare 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 VT-103 sound like?

Military designation.. 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

←VT-103

← VR40 VT-104 →Compare → 6SQ7

VT-103 Tetrode Vacuum Tube

Tetrode6.3V / 0.3AOctalSPICE

Sourceamplifiedparts 6SQ7 (= VT-103)Reviewed2026-05-29StatusDataModelCalcModelNorman KorenPDF

Beam power tetrode rated at 30W for high-power output stages

Datasheet ↗SPICE

VT-103 — RCA — tetrode vacuum tube — (1942)

100

91.0kΩ

6.0mA/V

11.0pF

0.2pF

7.00pF

GAIN100%

POWER75%

DRIVE9%

LINEARITY50%

SPECIFICATIONS

Heater6.3 V · 0.3 A

Max Plate Voltage750 V

Pa max30 W

Gain Factor100

gm6 mA/V

rp91.0 kΩ

Inter-electrode capacitances

Cgk11 pF

Cgp0.2 pF

Cpk7 pF

PinoutOctal

Era1942

RarityRare

HEATER6.3V / 0.3A

MAX PLATE750V / 30W

BASEoctal

Source datasheets

2 manufacturer datasheets cross-checked for VT-103

2 verified

TYPICAL OPERATING POINT

Va575V

Ia6.71mA

Vg-2.5V

Pd3.86W

RL182kΩ

Av38.4dB

EXECUTIVE SUMMARY

The VT-103 is a indirectly-heated beam tetrode from RCA, introduced around 1942. It provides a gain factor (μ) of 100 with 91.0kΩ plate resistance. Commonly used in preamp applications. Military designation.

APPLICATIONS

High-power output

Generic tetrode preamp stage

• PA/public address

VS 6SQ7

μ 0%Rp +0%Pd +5900%Full comparison →

HISTORY

Introduced1942ManufacturerRCA

Pre-War

VT-103 Datasheet

Local mirror · PDF

↗

METRIX TESTER

Test this tube on a Metrix

SIMILAR TETRODES

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