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Voltage - Dual Triode (similar) ·Triode-Triode

12SL7GT

Octal high-mu twin triode designed for resistance-coupled voltage amplification and phase inversion, providing two similar Class-A triode sections for low-level signal service.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 2
Base: 8BD
Socket code: IO
Base pins: 8
Nominal heater: 12.6 V / 150 mA

Description

High-mu twin triode used as a phase inverter and in resistance-coupled amplifier circuits.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 8BD
Socket code: IO
Base pins: 8
Nominal heater voltage: 12.6 V
Nominal heater current: 150 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

8BD - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN12G1	B	G1 — Control Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 8BD
PIN22P	B	P — Plate (Anode) EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 8BD
PIN32K	B	K — Cathode EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 8BD
PIN41G1	A	G1 — Control Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 8BD
PIN51P	A	P — Plate (Anode) EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 8BD
PIN61K	A	K — Cathode EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 8BD
PIN7H	—	H — Heater EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 8BD
PIN8H	—	H — Heater EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 8BD

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 44000 Ω
Transconductance: 0.0016 S
Amplification factor: 70
Max plate voltage: 300 V
Max plate dissipation: 1 W
Max cathode current: 10 mA

Published promoted fields populated semantically; identical repeated sections compressed.

Section 2

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 44000 Ω
Transconductance: 0.0016 S
Amplification factor: 70
Max plate voltage: 300 V
Max plate dissipation: 1 W
Max cathode current: 10 mA

Physical triode row restored under current one-row-per-physical-section policy.

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

Triode

Other

Plate voltage
250 V
ClassA;EachSection
Control-grid voltage
-2 V
ClassA;EachSection
Plate current
2.3 mA
ClassA;EachSection

Characteristic

Plate resistance
44000 Ω
EachSection
Transconductance
1600 µS
EachSection
Amplification factor
70
EachSection

Data set 02

1961 Ferranti Technical Handbook

Published operating points and test conditions from this source.

SECTION 1

Triode

Application

Application
Voltage amplifier / phase inverter

Data set 03

1966 Tung Sol Electronic Tubes 3 of 4

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Typical plate voltage
250 V
EachSection
Typical plate current
2.3 mA
EachSection
Typical grid voltage
-2 V
EachSection
Maximum plate voltage
300 V
PromotedValue
Maximum plate dissipation
1 W
PromotedValue

Capacitance

Grid-to-plate capacitance
2.8 pF
EachSection
Input capacitance
3.2 pF
EachSection
Output capacitance
3.4 pF
EachSection

Characteristics

Plate resistance
44000 ohm
PromotedValue
Transconductance
0.0016 A/V
PromotedValue
Amplification factor
70
PromotedValue

Data set 04

1971 RCA HB3 Binder 5 of 7

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;EachSection
Grid voltage
-2 V
ClassA;EachSection
Plate current
2.3 mA
ClassA;EachSection
Maximum plate voltage
300 V
EachSection
Plate dissipation
1 W
EachSection

Characteristic

Plate resistance
44000 ohm
EachSection
Transconductance
1600 uS
EachSection
Amplification factor
70
EachSection

Data set 05

1975 RCA RC30

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Peak Heater-Cathode Voltage
90 V
TypicalOperation;PublishedValue1
Peak Heater-Cathode Voltage
90 V
TypicalOperation;PublishedValue2
Plate Voltage
300 V
MaximumRating
Grid Voltage. Positive-bias value
0 V
MaximumRating
Plate Dissipation
1 W
MaximumRating
Maximum Plate Voltage
300 V
Section1
Maximum Plate Dissipation
1 W
Section1

Capacitance

Grid to Plate
2.8 pF
Capacitance;PublishedValue1
Grid to Plate
2.8 pF
Capacitance;PublishedValue2
Grid to Cathode and Heater
3.4 pF
Capacitance
Plate to Cathode and Heater
3.2 pF
Capacitance

Characteristic

Plate Voltage
250 V
Characteristic
Grid Voltage
-2 V
Characteristic
Plate Resistance (Approx. t
44000 ohm
Characteristic
Transconductance
11500 uS
Characteristic
Plato Current
2 mA
Characteristic
Plate Resistance
44000 ohm
Section1
Amplification Factor
70
Section1