12AL8

Medium-mu triode plus space-charge-grid tetrode for low-voltage detector/voltage-amplifier and power-amplifier service; tetrode output is only about 40 mW.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 2
Base: 9GS
Socket code: B9A
Base pins: 9
Nominal heater: 12.6 V / 550 mA

Description

Medium-mu triode plus space-charge-grid tetrode for low-voltage detector/voltage-amplifier and power-amplifier 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: 9GS
Socket code: B9A
Base pins: 9
Nominal heater voltage: 12.6 V
Nominal heater current: 550 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

9GS - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1Base Pin	A	P — Plate (Anode) Literal label 1P; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS
PIN2Base Pin	B	G2 — Screen Grid Literal label 2G2; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS
PIN3Base Pin	B	G1 — Control Grid Literal label 2G1; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS
PIN4Base Pin	—	H — Heater Literal label H; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS
PIN5Base Pin	—	H — Heater Literal label H; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS
PIN6Base Pin	A	P — Plate (Anode) Literal label 1P; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS
PIN7Base Pin	B	K — Cathode Literal label 2K; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS
PIN8Base Pin	A	G1 — Control Grid Literal label 1G1; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS
PIN9Base Pin	A	K — Cathode Literal label 1K; manufacturer confirmation pending	Unverified EIA Base Connections printed p132, 9GS

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 13000 Ω
Transconductance: 0.001 S
Amplification factor: 13
Max plate voltage: 30 V
Max plate dissipation: 1.5 W
Max cathode current: 20 mA

Published promoted fields populated semantically; identical repeated sections compressed.

Section 2

Tetrode

X-ray radiationInterelectrode capacitances

Plate resistance: 480 Ω
Transconductance: 0.015 S
Amplification factor: 7.2
Max plate voltage: 30 V
Max screen voltage: 16 V
Max plate dissipation: 2.5 W
Max screen dissipation: 0.75 W

Published promoted fields populated semantically; identical repeated sections compressed.

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

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 2

Tetrode

Other

TetrodePowerOutput
40 mW
Section2

Characteristic

TetrodeTransconductance
15000 uS
Section2

Data set 02

1966 Tung Sol Electronic Tubes 2 of 4

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Plate voltage
12.6 V
LowVoltageOperation
Control-grid voltage
-0.5 V
LowVoltageOperation
Plate current
4 mA
LowVoltageOperation

Characteristic

Amplification factor
72
LowVoltageOperation
Transconductance
4000 uS
LowVoltageOperation

SECTION 2

Tetrode

Other

Plate voltage
12.6 V
LowVoltageOperation
Control-grid voltage
-0.9 V
LowVoltageOperation
Plate current
0.5 mA
LowVoltageOperation
Power output
40 mW
LowVoltageOperation

Characteristic

Amplification factor
13
LowVoltageOperation
Transconductance
400 uS
LowVoltageOperation