3C4

Low-voltage directly heated power pentode designed for Class-A audio output. Its filamentary cathode and modest supply requirements suit battery-operated low-frequency power amplifiers.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: 6BX
Socket code: -
Base pins: 6
Nominal heater: 1.4 V / 50 mA

Description

Low-voltage directly heated power pentode for Class A audio output.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 6BX
Socket code: -
Base pins: 6
Nominal heater voltage: 1.4 V
Nominal heater current: 50 mA
Parallel heater voltage: 1.4 V
Parallel heater current: 50 mA
Series capable: Yes

6BX - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1F	—	F — Filament Source code F; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 6BX
PIN2P	A	P — Plate (Anode) Source code P; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 6BX
PIN3G2	A	G2 — Screen Grid Source code G2; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 6BX
PIN4IC	—	IC Source code IC; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 6BX
PIN5G3	A	G3 — Suppressor GridGroup 6BX5 Source code G3; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 6BX
PIN5FCT	—	FCT — Filament Center TapGroup 6BX5 Source code FCT; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 6BX
PIN6G1	A	G1 — Control Grid Source code G1; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 6BX
PIN7F	—	F — Filament Source code F; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 6BX

Section ratings

1 physical section, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances

Transconductance: 0.0014 S
Max plate voltage: 90 V
Max screen voltage: 90 V
Max plate dissipation: 0.6 W
Max screen dissipation: 0.2 W

Low-voltage directly heated power pentode for Class A audio output.

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
85 V
ClassA;ParallelFilaments
Screen-grid voltage
85 V
ClassA;ParallelFilaments
Grid No.1 bias
5.2 V
ClassA;ParallelFilaments
Plate current
5 mA
ClassA;ParallelFilaments
Screen-grid current
1.1 mA
ClassA;ParallelFilaments
Plate resistance
125000 ohm
ClassA;ParallelFilaments
Transconductance
1350 uS
ClassA;ParallelFilaments
Load resistance
13000 ohm
ClassA;ParallelFilaments
Power output
0.2 W
ClassA;ParallelFilaments

Data set 02

1961 Ferranti Technical Handbook

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

HeaterOrFilamentVoltage
1.4 V
HeaterOrFilamentCurrent
50 mA
CenterTappedFilament
1 boolean

Data set 03

1999 Philips 0-D

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Filament current
50 ma
Filament current 50 ma
Cathode current (withoutsizggf) max.2x3
1 ma
Cathode current (withoutsizggf) max.2x3.1 ma
Plate current 3.5
5 ma
Plate current 3.5 5.0 ma
Grid No.2 current 0.75
1.1 ma
Grid No.2 current 0.75 1.1 ma
Grid No
1 A
Grid No.1 A.C. voltage at 17 1.5 volts,rms