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Power - Pentode (NOT beam) ·Pentode

PEN428

Power/output pentode designed for audio-frequency output amplification in receiver or push-pull amplifier service.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
B7
Base pins
7
Nominal heater
4 V / 1.8 A

Description

The Mullard PEN428 is a high-power output pentode designed especially for Class AB push-pull audio amplifiers delivering about 20–30 W.

Socket description

Medium 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
B7
Base pins
7
Nominal heater voltage
4 V
Nominal heater current
1.8 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

Pentode

X-ray radiationInterelectrode capacitances
Max plate voltage
375 V
Max screen voltage
275 V

High-power audio output pentode.

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

1958 Mullard Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Power Output

    8 W

    ClassA; OneTube; PlateVoltage=250V

  • Power Output

    19 W

    ClassAB; PushPull; TwoTubes; PlateVoltage=250V

  • Power Output

    28 W

    ClassAB; PushPull; TwoTubes; PlateVoltage=375V