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6AU8

Medium-mu triode plus sharp-cutoff pentode combination; available documentation establishes the construction but does not support one dominant application strongly enough for reassignment.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 2
Base: 9DX
Socket code: B9A
Base pins: 9
Nominal heater: 6.3 V / 450 mA

Description

6AU8 is described in the supplied Tung-Sol datasheet as a sharp-cutoff pentode and medium-mu triode. Published maximum ratings and core section characteristics were extracted into the technical tables.

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: 9DX
Socket code: B9A
Base pins: 9
Nominal heater voltage: 6.3 V
Nominal heater current: 450 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

9DX - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN12K	B	K — Cathode EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN22G1	B	G1 — Control Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN32P	B	P — Plate (Anode) EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN4H	—	H — Heater EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN5H	—	H — Heater EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN61G3	A	G3 — Suppressor GridGroup 9DX6 EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN6IS	A	IS — Internal ScreenGroup 9DX6 EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN61K	A	K — CathodeGroup 9DX6 EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN71G1	A	G1 — Control Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN81G2	A	G2 — Screen Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX
PIN91P	A	P — Plate (Anode) EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9DX

Section ratings

2 physical sections, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances

Plate resistance: 150000 Ω
Transconductance: 0.007 S
Max plate voltage: 300 V
Max screen voltage: 300 V
Max plate dissipation: 3 W
Max screen dissipation: 1 W

Promoted from the printed maximum-rating/characteristic columns; operating points retained as section parameters.

Section 2

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 8200 Ω
Transconductance: 0.0049 S
Amplification factor: 40
Max plate voltage: 300 V
Max plate dissipation: 2.5 W

Promoted from the printed maximum-rating/characteristic columns; operating points retained as section parameters.

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

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate voltage
200 V
Pentode ClassA
Screen voltage
125 V
Pentode ClassA
Plate current
15 mA
Pentode ClassA
Screen current
3.4 mA
Pentode ClassA
Plate voltage
150 V
Triode ClassA
Plate current
8.5 mA
Triode ClassA

SECTION 2

Triode

Other

Plate voltage
200 V
Pentode ClassA
Screen voltage
125 V
Pentode ClassA
Plate current
15 mA
Pentode ClassA
Screen current
3.4 mA
Pentode ClassA
Plate voltage
150 V
Triode ClassA
Plate current
8.5 mA
Triode ClassA

Data set 02

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate Voltage
200 V
ClassA;PentodeSection
Screen Voltage
125 V
ClassA;PentodeSection

Characteristic

Plate Current
15 mA
ClassA;PentodeSection

SECTION 2

Triode

Other

Plate Voltage
150 V
ClassA;TriodeSection
Heater Warmup Time
11 s

Characteristic

Plate Current
9.5 mA
ClassA;TriodeSection

Data set 03

1965 Westinghouse Data Book

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate Voltage
200 V
PentodeUnit
Screen Voltage
125 V
PentodeUnit
Plate Current
9.5 mA
PentodeUnit
Screen Current
3.5 mA
PentodeUnit

Characteristic

Transconductance
5000 uS
GridToPlateCapacitanceMaximum
0.015 pF
Input Capacitance
5 pF
Output Capacitance
3.5 pF

SECTION 2

Triode

Characteristic

HeaterOrFilamentVoltage
6.3 V
HeaterOrFilamentCurrent
600 mA
ControlledWarmupHeater
1 boolean
Heater Warmup Time
11 s
Transconductance
7500 uS
Amplification Factor
60
Grid To Plate Capacitance
1.8 pF
Input Capacitance
2.8 pF
Output Capacitance
2 pF

Other

Plate Voltage
150 V
TriodeUnit
Plate Current
10 mA
TriodeUnit

Data set 04

1966 Tung Sol Electronic Tubes 1 of 4

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

Heater voltage
6.3 V
Published table
Heater current
600 mA
Published table
Pentode plate resistance
150000 ohm
PentodeSection
Pentode transconductance
7000 µS
PentodeSection
Triode plate resistance
8200 ohm
TriodeSection
Triode transconductance
4900 µS
TriodeSection
Triode amplification factor
40
TriodeSection

Other

Pentode plate voltage
200 V
PentodeSection
Pentode plate current
15 mA
PentodeSection
Triode plate voltage
250 V
TriodeSection
Triode plate current
9 mA
TriodeSection