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Power - Triode (over 1000V 100W) ·Triode

BR128

Forced-air-cooled tungsten-filament transmitting triode for VHF power amplification and oscillator service.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
-
Base pins
-
Nominal heater
12.5 V / 300 A

Description

The Marconi BR128 is a forced-air-cooled tungsten-filament transmitting triode for vhf power amplification and oscillation.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
-
Base pins
-
Nominal heater voltage
12.5 V
Nominal heater current
300 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

Triode

X-ray radiationInterelectrode capacitances
Transconductance
0.022 S
Amplification factor
24
Max plate voltage
12000 V
Max plate dissipation
12000 W
Max grid dissipation
2000 W

Highest published service maximums promoted; cooling and operating conditions preserved in 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

1955 Marconi

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Heater/filament voltage

    12.5 V

  • Heater/filament current

    300 A

  • Maximum plate voltage

    12000 V

  • Maximum plate dissipation

    12000 W

  • Maximum grid dissipation

    2000 W

  • Maximum frequency at full ratings

    100 MHz

  • Maximum filament starting current

    450 A

Characteristic

  • Amplification factor

    24

  • Transconductance

    22000 uS

Capacitance

  • Grid-plate capacitance

    28 pF

  • Plate-cathode capacitance

    1.5 pF

  • Grid-cathode capacitance

    44 pF

Construction

  • Cooling

    Forced air