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Power - Pentode (NOT beam) ·Pentode

7D8

High-slope audio power pentode with approximately 10 mA/V transconductance and 3.75 W published output.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
M7A
Base pins
7
Nominal heater
13 V / 650 mA

Description

High-slope power pentode with a 13 V heater, 10 mA/V transconductance, and approximately 3.75 W output.

Socket description

British/European 7-pin

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
M7A
Base pins
7
Nominal heater voltage
13 V
Nominal heater current
650 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
60000 Ω
Transconductance
0.01 S

Published Brimar values promoted where applicable; additional data retained as parameters.

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

1948 Brimar Radio Valve Manual

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Plate Voltage

    250 V

  • Plate Current

    32 mA

  • Screen Voltage

    250 V

  • Screen Current

    6 mA

  • Control Grid Voltage

    -6 V

  • Cathode Bias Resistor

    150 ohm

  • Optimum Load

    8500 ohm

  • Power Output

    3.75 W

Characteristic

  • Plate Resistance

    60000 ohm

  • Transconductance

    10000 µS

Data set 02

1958 Brimar Radio Valve No 7

Published operating points and test conditions from this source.

SECTION 1

Pentode

Application

  • Application

    Power output