Skip to main content
Tube Tinker — Electron Tube Database
Alternatives & variationsDownload PDF datasheet

Voltage Pentode or Tetrode (under 100V) ·Pentode

DF91

Equivalent designation printed with the 1T4 directly heated variable-mu RF/IF pentode. It provides controlled high-frequency gain while using a low-power filament suited to battery-operated receivers.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
B7G
Socket code
B7G
Base pins
7
Nominal heater
1.4 V / 50 mA

Description

Equivalent designation printed on the 1T4 source for the directly heated variable-mu RF/IF pentode.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
B7G
Socket code
B7G
Base pins
7
Nominal heater voltage
1.4 V
Nominal heater current
50 mA
Parallel heater voltage
1.4 V
Parallel heater current
50 mA
Series capable
Yes

B7G - 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
Plate resistance
800000 Ω
Transconductance
0.00075 S
Max plate voltage
90 V
Max screen voltage
67.5 V
Max plate dissipation
0.5 W
Max screen dissipation
0.2 W
Max cathode current
5.5 mA

RF/IF pentode for battery receivers.

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

1951 Mullard Valve and Service Manual

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

  • Anode Voltage

    90 V

  • Screen Voltage

    67.5 V

  • Anode Current

    3.5 mA

  • Screen Current

    1.4 mA

  • Control Grid Voltage for Low Transconductance

    -16 V

    Transconductance=10uA/V

Data set 02

1961 Ferranti Technical Handbook

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

  • Cutoff characteristic

    Variable-mu

Application

  • Application

    RF / IF amplifier

Data set 03

1963 Mullard

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

  • Filament Voltage

    1.4 V

    DCOnly

  • Filament Current

    50 mA

    DCOnly

  • Transconductance

    900 uS

    Representative

  • Plate Resistance

    500000 ohm

    Representative

  • Input Capacitance

    3.6 pF

  • Output Capacitance

    7.5 pF

  • Plate-Grid Capacitance

    0.01 pF

    Maximum

  • Grid Voltage at gm=10uS

    -16 V

    Representative

Other

  • Plate Voltage

    90 V

    RFAmplifier

  • Screen Voltage

    67.5 V

    RFAmplifier

  • Plate Current

    3.5 mA

    RFAmplifier

  • Screen Current

    1.4 mA

    RFAmplifier

  • Maximum Plate Voltage

    90 V

  • Maximum Screen Voltage

    67.5 V

  • Maximum Cathode Current

    5.5 mA

Data set 04

1963 Philips Electron Tubes Handbook V1

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

  • Plate capacitance

    7.5 pF

  • Grid-to-plate capacitance

    - to 0.01 pF

Other

  • Plate voltage

    90 V

    RF/IF amplifier

  • Screen voltage

    45 V

    RF/IF amplifier

  • Plate current

    1.8 mA

    RF/IF amplifier

  • Screen current

    0.65 mA

    RF/IF amplifier

Characteristic

  • Transconductance

    750 uS

    RF/IF amplifier

  • Plate resistance

    0.8 Mohm

Data set 05

1967 Mullard Receiving Tubes for Maintenance

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

  • Plate-to-Input Capacitance

    <0.01 pF

    PublishedCapacitance

  • Input Capacitance

    3.6 pF

    PublishedCapacitance

  • Output Capacitance

    7.5 pF

    PublishedCapacitance

Other

  • Plate Voltage

    90 V

    RFOrIFAmplifier

  • Screen Voltage

    67.5 V

    RFOrIFAmplifier

  • Plate Current

    3.5 mA

    RFOrIFAmplifier

  • Screen Current

    1.4 mA

    RFOrIFAmplifier

  • Transconductance

    900 uS

    RFOrIFAmplifier

  • Plate Resistance

    500 kohm

    RFOrIFAmplifier

  • Grid Voltage for 10uS Transconductance

    -16 V

    RFOrIFAmplifier

  • Plate Voltage

    90 V

    PublishedLimits

  • Screen Supply Voltage

    90 V

    PublishedLimits

  • Screen Voltage

    67.5 V

    PublishedLimits

  • Cathode Current

    5.5 mA

    PublishedLimits

Data set 06

1968 Mazda Belvu

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

  • Heater or filament voltage

    1.4 V

    Published nominal value

  • Heater or filament current

    50 mA

    Published nominal value

  • Transconductance

    875 µS

    Published operating characteristic

  • Transconductance

    875 µS

    67.5 V operating condition

Data set 07

1999 Philips 0-D

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Parallel heater voltage

    1.4 V

    Published datasheet value

  • Series heater voltage

    1.3 V

    Published datasheet value

  • Anode voltage

    45 V

    Published datasheet value

  • Screen-grid voltage

    45 V

    Published datasheet value

  • Anode current

    1.7 mA

    Published datasheet value

  • Screen-grid current

    0.7 mA

    Published datasheet value

Characteristics

  • Transconductance

    700 µS

    Published datasheet value

  • Internal resistance

    0.39 MΩ

    Published datasheet value

  • Screen-grid amplification factor

    11

    Published datasheet value

  • Equivalent noise resistance

    20 kΩ

    Published datasheet value

  • Anode capacitance

    7.5 pF

    Published datasheet value

  • Grid capacitance

    3.6 pF

    Published datasheet value

  • Anode-control-grid capacitance

    - to 0.01 pF

    Published datasheet value