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6L6

Classic beam-power audio-output tube for single-ended and push-pull amplifiers, offering substantial reserve power and widely used in radio, hi-fi, and musical-instrument equipment.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: 7AC
Socket code: IO
Base pins: 8
Nominal heater: 6.3 V / 900 mA

Description

Beam power tube used in audio-amplifier output stages where ample reserve power-delivering ability is desired.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 7AC
Socket code: IO
Base pins: 8
Nominal heater voltage: 6.3 V
Nominal heater current: 900 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

7AC - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1Pin 1	—	NC	Verified 12L6GT/25L6GT manufacturer basing, 7AC
PIN2Pin 2	—	H — Heater	Verified 12L6GT/25L6GT manufacturer basing, 7AC
PIN3Pin 3	A	P — Plate (Anode)	Verified 12L6GT/25L6GT manufacturer basing, 7AC
PIN4Pin 4	A	G2 — Screen Grid	Verified 12L6GT/25L6GT manufacturer basing, 7AC
PIN5Pin 5	A	G1 — Control Grid	Verified 12L6GT/25L6GT manufacturer basing, 7AC
PIN7Pin 7	—	H — Heater	Verified 12L6GT/25L6GT manufacturer basing, 7AC
PIN8Pin 8	A	BP — Beam-Forming PlateGroup AC8	Verified 12L6GT/25L6GT manufacturer basing, 7AC
PIN8Pin 8	A	K — CathodeGroup AC8	Verified 12L6GT/25L6GT manufacturer basing, 7AC

Section ratings

1 physical section, each with unique specifications.

Section 1

Beam Power

X-ray radiationInterelectrode capacitances

Plate resistance: 35000 Ω
Transconductance: 0.0053 S
Max plate voltage: 360 V
Max screen voltage: 270 V
Max plate dissipation: 19 W
Max screen dissipation: 2.5 W

Audio beam-power output section.

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

1937 Raytheon Radio Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

Maximum plate voltage
400 V
Published datasheet rating
Plate voltage
250 V
ClassA
Maximum screen dissipation
3.5 W
BeamPower
Class-A fixed-bias plate voltage
375 V
ClassA FixedBias
Push-pull plate voltage
250 V
ClassA PushPull TwoTubes
Push-pull power output
14.5 W
ClassA PushPull TwoTubes
Class-AB push-pull plate voltage
400 V
ClassAB PushPull TwoTubes

Characteristic

Plate resistance
22500 ohm
Published datasheet characteristic
Transconductance
6000 µS
Published datasheet characteristic
Heater voltage
6.3 V
Published heater rating
Heater current
900 mA
Published heater rating
Class-A fixed-bias plate resistance
22500 ohm
ClassA FixedBias
Class-A fixed-bias transconductance
6000 µS
ClassA FixedBias

Data set 02

1940 RCA

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Characteristics

Heater voltage
6.3 V
Published nominal value
Heater current
900 mA
Published nominal value
Transconductance
6000 µS
Published operating characteristic
Amplification factor
135
Published operating characteristic

Other

Single-ended audio power output
11 W
Maximum-ratings discussion
Push-pull audio power output
60 W
PushPull
Push-pull audio power output
34 W
PushPull; Load=6600 ohm; no grid-driving power

Data set 03

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Application

Service
Audio power amplifier
PushPull

Data set 04

1953 RFT Rundfunk Technik

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

HeaterVoltageNominal
6.3 V
Nominal
HeaterCurrentNominal
1.1 A
Nominal
Maximum Plate Voltage
360 V
Maximum Screen Voltage
270 V
Maximum Plate Dissipation
19 W
Maximum Screen Dissipation
2.5 W

Characteristic

Transconductance
5200 µS
Typical
Plate Resistance
33000 ohm
Typical

Data set 05

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

Load resistance
2500 Ω
OneTube
Power output
6.5 W
OneTube

Data set 06

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

Plate Voltage
300 V
ClassA PentodeConnection
Screen Voltage
200 V
ClassA PentodeConnection
Plate Voltage
250 V
ClassA TriodeConnection
Plate Voltage
360 V
ClassAB PushPull PentodeConnection
Screen Voltage
270 V
ClassAB PushPull PentodeConnection

Characteristic

Plate Current
48 mA
ClassA PentodeConnection
Power Output
6.5 W
ClassA PentodeConnection
Power Output
1.4 W
ClassA TriodeConnection

Data set 07

1966 Tung Sol Electronic Tubes 2 of 4

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

Plate voltage
250 V
ClassA
Screen voltage
250 V
ClassA
Power_output
6.5 W
ClassA,OneTube
Power_output
26.5 W
PushPull,TwoTubes

Characteristic

Transconductance
5300 uS
ClassA
Plate resistance
35000 ohm
ClassA
Plate_current
72 mA
ClassA,OneTube
Amplification_factor
8
TriodeConnection

Capacitance

Input capacitance
3 pF
Section1
Output capacitance
3 pF
Section1

Data set 08

1971 RCA HB3 Binder 5 of 7

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

Heater voltage nominal
6.3 V
Heater current
900 mA
Voltage
63 V
Published source row
Current
9 A
Published source row

Capacitance

grid No
3
Published source row
grid No (value 2)
2
Published source row
grid No
3
Published source row
grid No (value 2)
2
Published source row
^e PLATE VOLTAGE
275 V
Published source row
PLATE DISSIPATION
19 W
Published source row

Characteristics

Plate Voltage
250 V
Published source row
Plate Voltage (value 2)
250 V
Published source row
Voltage
-20 V
Published source row
Peak AF Grid-No.l Voltage
20 V
Published source row
Peak AF Grid-No.l Voltage (value 2)
20 V
Published source row
ax.-Signal Plate Current
44 mA
Published source row
ax.-Signal Plate Current (value 2)
42 mA
Published source row
Amplification Factor
8
Published source row
Plate Resistance (Approx.)
1700 ohm
Published source row
Transconductance
4700 µS
Published source row
Load Resistance
5000 ohm
Published source row
Load Resistance (value 2)
6000 ohm
Published source row
Total Harnanic Distortion
5 %
Published source row
Total Harnanic Distortion (value 2)
6 %
Published source row
ax.-Signal Power Output
1.4 W
Published source row
ax.-Signal Power Output (value 2)
1.3 W
Published source row

Data set 09

1975 RCA RC30

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

Heater Voltage
6.3 V
Nominal
Heater Current
900 mA
Nominal
Peak Heater-Cathode Voltage
180 V
Plate Voltage
250 V
ClassA;PlateVoltage=250V
Screen Voltage
250 V
ClassA;PlateVoltage=250V
Control Grid Voltage
-14 V
ClassA;PlateVoltage=250V
Zero-Signal Plate Current
72 mA
ClassA;PlateVoltage=250V
Zero-Signal Screen Current
5 mA
ClassA;PlateVoltage=250V
Load Resistance
2500 ohm
ClassA;PlateVoltage=250V
Total Harmonic Distortion
10 %
ClassA;PlateVoltage=250V
Maximum-Signal Power Output
6.5 W
ClassA;PlateVoltage=250V
Plate Voltage
300 V
ClassA;PlateVoltage=300V
Screen Voltage
200 V
ClassA;PlateVoltage=300V
Control Grid Voltage
-12.5 V
ClassA;PlateVoltage=300V
Zero-Signal Plate Current
48 mA
ClassA;PlateVoltage=300V
Zero-Signal Screen Current
2.5 mA
ClassA;PlateVoltage=300V
Load Resistance
4500 ohm
ClassA;PlateVoltage=300V
Total Harmonic Distortion
11 %
ClassA;PlateVoltage=300V

Capacitance

Grid No.1-to-Plate Capacitance
0.4 pF
Grid No.1 Input Capacitance
10 pF
Plate Output Capacitance
12 pF

Characteristic

Plate Resistance
22500 ohm
ClassA;PlateVoltage=250V
Transconductance
6000 uS
ClassA;PlateVoltage=250V
Plate Resistance
35000 ohm
ClassA;PlateVoltage=300V
Transconductance
5300 uS
ClassA;PlateVoltage=300V