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Power - Triode Single (under 10W) ·Triode

ML4

Classic Marconi/Osram directly heated audio power triode for early receiver output stages. It combines about 5 W plate dissipation with low plate resistance and useful transformer-coupled output capability.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: B4
Base pins: 5
Nominal heater: 4 V / 1 A

Description

OSRAM ML4 triode for amplification, detection, or power-output service as specified in the supplied datasheet.

Socket description

European 4-pin base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: B4
Base pins: 5
Nominal heater voltage: 4 V
Nominal heater current: 1 A
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 2860 Ω
Transconductance: 0.0042 S
Amplification factor: 12
Max plate voltage: 250 V
Max plate dissipation: 5 W

Published characteristics/ratings were promoted when unambiguous; remaining operating values are preserved in TUBE_SECTION_PARAMETER.

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

192X Marconi Valve

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Published operating data
See source
Operating curves/table are present on the approved one-page source; values not promoted unless unambiguous in searchable text.

Data set 02

1937 Osram Valves

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Optimum load resistance
7000 ohm
Published operating data

Data set 03

193X Osram

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Heater/Filament Voltage
4 V
Published datasheet value
Heater/Filament Current
1 A
Published datasheet value
Maximum Anode Voltage
250 V
Published datasheet value
Maximum Anode Dissipation
5 W
Published datasheet value

Characteristics

Plate Resistance
2860 ohm
Published datasheet value
Mutual Conductance
4200 µS
Published datasheet value
Amplification Factor
12
Published datasheet value

Data set 04

1955 Marconi

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Filament/heater voltage
4 V
Filament/heater current
1 A
Maximum anode voltage
200 V
Maximum anode dissipation
5 W

Characteristic

Amplification factor
12
Transconductance
4200 uS
Plate resistance
2860 ohm