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Voltage - Dual Triode (similar) ·Triode-Triode

12AU7

Medium-mu twin triode for general amplification, phase inversion, oscillators, and multivibrators, offering relatively low plate resistance and greater current capability than high-mu preamplifier triodes.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 2
Base: 9A
Socket code: B9A
Base pins: 9
Nominal heater: 12.6 V / 150 mA

Description

Medium-mu dual triode represented on the 7AU7 family page; used for amplifier and television oscillator/deflection service.

Socket description

Small-button Noval 9-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 9A
Socket code: B9A
Base pins: 9
Nominal heater voltage: 12.6 V
Nominal heater current: 150 mA
Parallel heater voltage: 6.3 V
Parallel heater current: 300 mA
Series capable: Yes

9A - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN12P	B	P — Plate (Anode) EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN22G1	B	G1 — Control Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN32K	B	K — Cathode EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN4H	—	H — Heater EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN5H	—	H — Heater EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN61P	A	P — Plate (Anode) EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN71G1	A	G1 — Control Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN81K	A	K — Cathode EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN9HCT	—	HCT — Heater Center Tap EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 6500 Ω
Transconductance: 0.0022 S
Amplification factor: 17
Max plate voltage: 300 V
Max plate dissipation: 2.75 W
Max cathode current: 20 mA

Representative section for two equal triode systems.

Section 2

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 6500 Ω
Transconductance: 0.0022 S
Amplification factor: 17
Max plate voltage: 300 V
Max plate dissipation: 2.75 W
Max cathode current: 20 mA

Second identical physical triode section; added to align rows with SectionCount.

Source-dependent data

Operating conditions by source

Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.

Data set 01

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Plate Resistance
7700 ohm
Transconductance
2200 µS
Amplification Factor
17

Other

Maximum Plate Voltage
330 V
Maximum Plate Dissipation
3 W
Heater Voltage Series
12.6 V
Heater Current Series
150 mA
Heater Voltage Parallel
6.3 V
Heater Current Parallel
300 mA

Data set 02

1955 Marconi

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Series heater voltage
12.6 V
Series heater current
150 mA
Parallel heater voltage
6.3 V
Parallel heater current
300 mA
Maximum plate voltage
300 V
Maximum plate dissipation per section
2.75 W
Typical plate voltage
250 V

Characteristic

Amplification factor
17
Transconductance
2200 uS

Capacitance

Grid-plate capacitance
1.5 pF
Grid-cathode capacitance
1.6 pF
Plate-cathode capacitance
0.5 pF

Data set 03

1958 Amperex Industrial

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Plate voltage
250 V
Published table
Plate current
10.5 mA
Published table
Control-grid bias
-8.5 V
VoltageAmplifier

Characteristic

Plate resistance
7700 ohm
Published table
Transconductance
2200 µS
Published table
Amplification factor
17
Published table
Heater/filament voltage
6.3 V
Published rating
Heater/filament current
300 mA
Published rating
Series heater voltage
12.6 V
SeriesHeater
Series heater current
150 mA
SeriesHeater

Data set 04

1958 Brimar Radio Valve No 7

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Heater Voltage
12.6 V
Heater Current
150 mA

Data set 05

195X Tesla

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

Interelectrode capacitances
Published
See source sheet for electrode-specific capacitance values

Data set 06

1961 Ferranti Technical Handbook

Published operating points and test conditions from this source.

SECTION 1

Triode

Application

Application
Amplifier / phase inverter / oscillator / multivibrator

Data set 07

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Plate Resistance
7700 ohm
AlternateOperatingPoint
Transconductance
2200 uS
AlternateOperatingPoint

Data set 08

1963 Amperex Condensed

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Heater voltage
6.3 V
Published heater rating
Heater current
300 mA
Published heater rating
Amplification factor
17
VoltageAmplifier
Plate resistance
7700 ohm
VoltageAmplifier
Transconductance
2200 µS
VoltageAmplifier
Series heater voltage
12.6 V
SeriesHeater
Series heater current
150 mA
SeriesHeater

Other

Plate voltage
250 V
VoltageAmplifier
Control-grid bias
-8.5 V
VoltageAmplifier
Plate current
10.5 mA
VoltageAmplifier

Data set 09

1965 Sylvania Electronic Tubes Vol3

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Heater voltage
12.6 V
Heater current
150 mA
Plate voltage
250 V
ClassA

Characteristic

Plate resistance
7700 ohm
ClassA
Transconductance
2200 uS
ClassA
Amplification factor
17
ClassA

Data set 10

1965 Westinghouse Data Book

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Heater Voltage
12.6 V
Heater Current
150 mA
Plate Current
10.5 mA
Plate Resistance
7700 ohm
Transconductance
2200 uS
Amplification Factor
17
Grid To Plate Capacitance
2.4 pF
Input Capacitance
3.3 pF
Output Capacitance
0.5 pF

Other

Plate Voltage
250 V
EachUnit
Grid Voltage
-8.5 V
EachUnit

Data set 11

1966 Tung Sol Electronic Tubes 2 of 4

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Plate voltage
250 V
ClassA;EachSection
Plate current
10.5 mA
ClassA;EachSection
Grid voltage
-24 V
ClassA;EachSection

Characteristic

Plate resistance
7700 ohm
ClassA;EachSection
Transconductance
2200 uS
ClassA;EachSection
Amplification factor
17
ClassA;EachSection

Capacitance

Grid-to-plate capacitance
1.7 pF
EachSection
Input capacitance
1.8 pF
EachSection
Output capacitance
1.8 pF
EachSection

Data set 12

1975 RCA RC30

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Peak Heater-Cathode Voltage
200 V
AbsoluteValue
Average Heater-Cathode Voltage
100 V
AbsoluteValue
Peak Negative-Pulse Grid Voltage
660 V
HorizontalDeflectionOscillator
Peak Cathode Current
330 mA
HorizontalDeflectionOscillator
Peak Positive-Pulse Plate Voltage
1200 V
VerticalDeflectionAmplifier

Capacitance

Grid to Plate Capacitance
1.5 pF
EachUnit
Grid to Cathode and Heater Capacitance
1.6 pF
EachUnit

Characteristic

Plate Voltage
250 V
ClassA;EachUnit
Plate Current
10.5 mA
ClassA;EachUnit

Data set 13

2026 Genalex Rebrand

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Transconductance
1700 to 3000 µS
Plate 250 V; grid -8.5 V
Plate Current
8.8 to 12 mA
Plate 250 V; grid -8.5 V

Data set 14

2026 JJ Electronic

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Ik
20 mA
Published value

Characteristics

Ua
250 V
Published value
Ug
-8.5 V
Published value
Ia
10.5 mA
Published value
S
2200 µS
Published value
Ri
7.7 kΩ
Published value
µ
17
Published value

Capacitance

cg/k
1.9
Published value
ca
1.9
Published value
cg/a
1.63
Published value
Ub
250
Published value
Ia
0.7
Published value
Uo/Ug1
11
Published value
U0
15
Published value

Data set 15

2026 Mullard Rebrand

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

Heater current at 6.3 V
300 to 350 mA
Published min/max range
Heater current at 12.6 V
150 to 175 mA
Published min/max range