N78

Marconi miniature high-slope output pentode designed for receiver power stages. Its increased transconductance provides useful audio output from compact receiving equipment.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: B7G
Base pins: 7
Nominal heater: 6.3 V / 640 mA

Description

The Marconi N78 is a miniature high-slope output pentode for receiver power stages.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: B7G
Base pins: 7
Nominal heater voltage: 6.3 V
Nominal heater current: 640 mA
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

Plate resistance: 40000 Ω
Transconductance: 0.0105 S
Max plate voltage: 250 V
Max screen voltage: 250 V
Max plate dissipation: 9 W
Max screen dissipation: 3 W

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

1955 Marconi

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Heater voltage
6.3 V
Heater current
640 mA
Maximum plate voltage
250 V
Maximum screen voltage
250 V
Maximum plate dissipation
9 W
Maximum screen dissipation
3 W

Characteristic

Transconductance
10500 uS
Plate resistance
40000 ohm

Application

Primary application
Miniature high-slope output pentode for receiver power stages.