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Power - Tetrode (NOT beam) (over 1000V 100W) ·Tetrode

4X250F

26.5 V heater variant of the 4X250B VHF/UHF transmitting tetrode family.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
B8G
Base pins
8
Nominal heater
26.5 V / 500 mA

Description

26.5 V heater variant of the forced-air-cooled 4X250B external-anode tetrode family.

Socket description

Loctal 8-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
B8G
Base pins
8
Nominal heater voltage
26.5 V
Nominal heater current
500 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

Tetrode

X-ray radiationInterelectrode capacitances
Amplification factor
5
Max plate voltage
2000 V
Max screen voltage
300 V
Max plate dissipation
250 W
Max screen dissipation
12 W
Max grid dissipation
2 W
Max cathode current
250 mA

Promoted from printed maximum-rating and general-characteristics tables.

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

1962 Eimac

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Capacitance

  • Grid-Plate S 0.04 puf )

    0.04 pF

  • Output - - - - - - - - - . 4.7 puf

    4.7 pF

Other

  • Maximum plate voltage

    2000 V

  • Maximum screen voltage

    300 V

  • Maximum plate dissipation

    250 W

  • Maximum screen dissipation

    12 W

  • Maximum grid dissipation

    2 W

Data set 02

1963 Amperex Condensed

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Other

  • Plate voltage

    2000 V

    RFAmplifierOrOscillator; ClassC; Telegraphy

  • Plate current

    250 mA

    RFAmplifierOrOscillator; ClassC; Telegraphy

  • RF output power

    410 W

    RFAmplifierOrOscillator; ClassC; Telegraphy

  • Grid voltage

    -90 V

    RFAmplifierOrOscillator; ClassC; Telegraphy

  • Grid current

    12 mA

    RFAmplifierOrOscillator; ClassC; Telegraphy

  • Maximum frequency at full input rating

    500 MHz

  • Screen voltage

    250 V

    RFAmplifierOrOscillator; ClassC; Telegraphy

Capacitance

  • Grid-to-plate capacitance

    0.03 pF

  • Grid-to-filament/cathode capacitance

    15.7 pF

  • Plate-to-filament/cathode capacitance

    4.5 pF