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Power - Pentode (NOT beam) ·Pentode

7A3

Power/output pentode designed for low-frequency or audio-frequency output amplification.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
IO
Base pins
8
Nominal heater
4 V / 2 A

Description

The BRIMAR 7A3 is a high-slope power pentode with a 4.0 V, 2.0 A heater and 10 mA/V mutual conductance.

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
4 V
Nominal heater current
2 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
Plate resistance
60000 Ω
Transconductance
0.01 S
Max plate voltage
250 V
Max screen voltage
250 V

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

Characteristics

  • Anode Voltage

    250 V

  • Anode 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

Data set 02

1958 Brimar Radio Valve No 7

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Power output

    3.75 W