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

4X250B

Forced-air-cooled transmitting tetrode producing roughly 410 W RF output with full input rating to approximately 500 MHz.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: B8G
Base pins: 8
Nominal heater: 6 V / 2.1 A

Description

4X250B is a Tetrode device. Forced-air-cooled external-anode tetrode with brazed radiator; interchangeable with 4X150A where higher plate dissipation is required.

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: 6 V
Nominal heater current: 2.1 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

Tetrode

X-ray radiationInterelectrode capacitances

Transconductance: 0.012 S
Amplification factor: 5.2
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

1958 Amperex Industrial

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

Data set 02

1962 Eimac

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Capacitance

fier circuit will deliver up to 300 watts of Input 18.5 upf
18.5 pF
useful power output at 400mc, although Output 4.7 ppf
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 03

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

Data set 04

1965 Eimac Tube Manual

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Characteristic

Heater/Filament Voltage
6 V
Heater/Filament Current
2.3-2.9 A
Amplification Factor
5.2
Transconductance
12000 uS

Other

Maximum DC Plate Voltage
2000 V
Maximum DC Screen Voltage
400 V
Maximum Plate/Cathode Current
250 mA
Maximum Plate Dissipation
250 W
Maximum Screen Dissipation
12 W
Maximum Grid Dissipation
2 W
Frequency for Maximum Ratings
500 MHz
Typical Plate Output Power
390 W
UHF Plate Output Power
225 W
500 MHz

Construction

Cooling
Forced air