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Tube Tinker — Electron Tube Database
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Power - Beam (NOT sweep) ·BeamPower

HK257B

Radiation-cooled Gammatron beam pentode with exceptional VHF performance, high transconductance, and very low feedback allowing operation without neutralization.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
-
Base pins
7
Nominal heater
5 V / 7.5 A

Description

75-watt radiation-cooled beam pentode with exceptional very-high-frequency performance, high transconductance, and operation without neutralization. The source describes Gammatron construction using tantalum electrode structures and a thoriated-tungsten filament where applicable.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
-
Base pins
7
Nominal heater voltage
5 V
Nominal heater current
7.5 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

Beam Power

X-ray radiationInterelectrode capacitances
Max plate voltage
4000 V
Max screen voltage
750 V
Max plate dissipation
75 W
Max screen dissipation
25 W
Max cathode current
150 mA

Published maximum ratings and characteristics promoted from the datasheet; typical application values remain parameter rows.

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

1944 Heintz and Kaufman

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Characteristic

  • Filament Voltage

    5 V

  • Filament Current

    7.5 A

  • Plate-Grid Capacitance

    0.08 pF

    InterelectrodeCapacitance

  • Input Capacitance

    10.5 pF

    InterelectrodeCapacitance

  • Output Capacitance

    4.7 pF

    InterelectrodeCapacitance

Other

  • Normal Plate Dissipation

    75 W

  • Maximum Plate Voltage

    4000 V

  • Maximum Average Plate Current

    150 mA

  • Maximum Screen Input

    25 W

  • RF Class C Unmodulated Maximum Screen Current

    30 mA

    ClassC;Unmodulated

  • RF Class C Unmodulated Maximum Control Grid Current

    25 mA

    ClassC;Unmodulated

  • RF Class C Plate-Modulated Maximum Plate Voltage

    3000 V

    ClassC;PlateModulated

  • RF Class C Plate-Modulated Maximum Screen Voltage

    600 V

    ClassC;PlateModulated