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

Voltage - Dual Triode (similar high frequency) ·Triode-Triode

7F8

High-transconductance double triode designed for operation into the hundreds of megahertz, including push-pull UHF amplification and FM or television frequency-converter service.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
8BW
Socket code
LOCTAL8
Base pins
8
Nominal heater
8.3 V / 300 mA

Description

The 7F8 combines two high-transconductance triodes for operation into the hundreds of megacycles, including push-pull UHF amplification and FM/television converter service.

Socket description

Loctal 8-contact base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
8BW
Socket code
LOCTAL8
Base pins
8
Nominal heater voltage
8.3 V
Nominal heater current
300 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

8BW - Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
14500 Ω
Transconductance
0.0033 S
Amplification factor
48
Max plate voltage
300 V
Max plate dissipation
3.5 W

Promoted fields mapped by printed headings; additional data retained in parameters.

Section 2

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
14500 Ω
Transconductance
0.0033 S
Amplification factor
48
Max plate voltage
300 V
Max plate dissipation
3.5 W

Second physical triode section; added to align rows with SectionCount.

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

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Triode

Capacitance

  • Input capacitance

    2.8 pF

    EachSection

  • Output capacitance

    1.4 pF

    EachSection

  • Grid-to-plate capacitance

    1.6 pF

    EachSection

Other

  • Typical plate voltage

    250 V

    ClassA;EachSection

  • Cathode resistor

    500 Ohm

    ClassA;EachSection

  • Typical plate current

    6 mA

    ClassA;EachSection

Characteristic

  • Transconductance

    3300 uS

    EachSection

  • Amplification factor

    48

    EachSection

Data set 02

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Voltage

    250 V

    EachUnit

Characteristic

  • Plate Current

    9 mA

    EachUnit

Data set 03

1966 Tung Sol Electronic Tubes 2 of 4

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate_voltage

    150 V

    Section1,Section2,ClassA

  • Grid_voltage

    -2 V

    Section1,Section2,ClassA

Characteristic

  • Plate_current

    6 mA

    Section1,Section2,ClassA

  • Amplification_factor

    48

    Section1,Section2,ClassA

  • Transconductance

    6000 uS

    Section1,Section2,ClassA

Capacitance

  • Grid-to-plate capacitance

    2.1 pF

    Section1,Section2

  • Input capacitance

    4 pF

    Section1,Section2

  • Output capacitance

    1.3 pF

    Section1,Section2

Data set 04

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • designed for use as a grounded-grid radio-frequency up to

    300 MHz

    Published datasheet line; semantic text-layer recovery

  • Heater Voltage (A-C or D-C)

    8.3 V

    Published datasheet line; semantic text-layer recovery

  • Heater Current

    300 mA

    Published datasheet line; semantic text-layer recovery

  • Plate Voltage e e e e e e e e e

    300 V

    Published datasheet line; semantic text-layer recovery

  • Plate Dissipation (Total for Both Sections)

    3.5 W

    Published datasheet line; semantic text-layer recovery

  • Grid Voltage (Positive Bias Value)

    0 V

    Published datasheet line; semantic text-layer recovery

  • Peak Heater-Cathode Voltage

    90 V

    Published datasheet line; semantic text-layer recovery

  • pPiate Voltage

    250 V

    Published datasheet line; semantic text-layer recovery

  • Cathode-Bias Resustor#

    500 Ohm

    Published datasheet line; semantic text-layer recovery

Characteristic

  • Plate Resistance (Approxnmate)

    14500 Ohm

    Published datasheet line; semantic text-layer recovery

  • Transconductance C

    3300 uS

    Published datasheet line; semantic text-layer recovery