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DL33

Centre-tapped-filament battery output pentode designed for Class-A audio service. Its filament arrangement provides flexibility for portable receiver power supplies while delivering low-frequency output power.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: IO
Base pins: 8
Nominal heater: 2.8 V / 50 mA

Description

Centre-tapped-filament battery output pentode for Class A audio service.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: IO
Base pins: 8
Nominal heater voltage: 2.8 V
Nominal heater current: 50 mA
Parallel heater voltage: 1.4 V
Parallel heater current: 100 mA
Series capable: Yes

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

Pentode

X-ray radiationInterelectrode capacitances

Plate resistance: 100000 Ω
Transconductance: 0.0022 S
Max plate voltage: 110 V
Max screen voltage: 110 V
Max cathode current: 12 mA

Published ratings and characteristics promoted semantically from the approved source; repeated identical physical sections compressed where applicable.

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

1951 Mullard Valve and Service Manual

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate Voltage
110 V
ParallelFilament
Screen Voltage
110 V
ParallelFilament
Plate Current
10 mA
ParallelFilament
Power Output
400 mW
ParallelFilament

Characteristic

Transconductance
2200 µS
ParallelFilament
Plate Resistance
100000 ohm
ParallelFilament

Data set 02

1963 Mullard

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

HeaterOrFilamentVoltage
2.8 V
HeaterOrFilamentCurrent
50 mA

Other

Plate Voltage
90 V
ClassA;SeriesFilament
Screen Voltage
90 V
ClassA;SeriesFilament
Control Grid Voltage
-4.5 V
ClassA
Plate Current
8 mA
ClassA
Screen Current
1 mA
ClassA
Load Resistance
8 kohm
ClassA
Power Output
230 mW
ClassA
Power Output
400 mW
ClassA;ParallelFilament;PlateVoltage=110V
GridResistanceMaximum
1 Mohm