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7438

Reliable subminiature pentode for guided-weapon equipment, with a short suppressor base allowing grid 3 to serve as a second control electrode. Its construction supports specialized signal-control functions under severe vibration.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: B8D/F
Socket code: SUBMINIATURE8
Base pins: 8
Nominal heater: 6.3 V / 175 mA

Description

Reliable subminiature short-suppressor-base pentode with the suppressor grid usable as a second control electrode, intended for guided-weapon equipment.

Socket description

Subminiature 8-lead base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: B8D/F
Socket code: SUBMINIATURE8
Base pins: 8
Nominal heater voltage: 6.3 V
Nominal heater current: 175 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

B8D/F - 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

Transconductance: 0.0025 S
Amplification factor: 34
Max plate voltage: 350 V
Max screen voltage: 350 V
Max plate dissipation: 1 W
Max screen dissipation: 0.4 W
Max cathode current: 12 mA

Promoted values are taken directly from the supplied datasheet; additional ratings, characteristics and operating points are preserved in TUBE_SECTION_PARAMETER.

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

1963 Mullard

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate supply voltage maximum
350 V
Screen-grid supply voltage maximum
350 V

Capacitance

Grid1-to-plate capacitance maximum
0.015 pF
ExternalShield
Grid3-to-plate capacitance maximum
3 pF
ExternalShield
Grid3-to-all-electrodes capacitance
6.5 pF
ExternalShield
Input capacitance
4.2 pF
ExternalShield
Output capacitance
3.1 pF
ExternalShield

Characteristics

Plate voltage
100 V
Screen-grid voltage
100 V
Plate current
3 mA
Screen-grid current
2.25 mA
Grid1 transconductance
2500 uS
Grid3 transconductance
350 uS
Grid3Bias=-2V
Screen-to-control-grid amplification factor
34 ratio
Maximum noise output voltage
200 mV
Vibration=20g;60-1000Hz