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Tube Tinker — Electron Tube Database
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Voltage - Dual Triode (similar high frequency) ·Triode-Triode

3FX7

High-transconductance medium-mu twin triode designed for low-noise VHF cascode amplification in television tuners, with low interelectrode capacitance supporting high-frequency operation.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
-
Socket code
B9A
Base pins
9
Nominal heater
3.5 V / 600 mA

Description

Medium-mu twin triode with high transconductance, low noise and low interelectrode capacitance for cascode TV tuners.

Socket description

Small-button Noval 9-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
B9A
Base pins
9
Nominal heater voltage
3.5 V
Nominal heater current
600 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

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
3800 Ω
Transconductance
0.0095 S
Amplification factor
36
Max plate voltage
100 V
Max plate dissipation
1.7 W
Max cathode current
20 mA

Unit 1 of twin triode; section-specific capacitances published.

Section 2

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
3800 Ω
Transconductance
0.0095 S
Amplification factor
36
Max plate voltage
100 V
Max plate dissipation
1.7 W
Max cathode current
20 mA

Unit 2 of twin triode; section-specific capacitances published.

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

1982 Toshiba

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Voltage

    90 V

    ClassA1

  • Grid Voltage

    -1 V

    ClassA1

  • Plate Current

    9 mA

    ClassA1

Capacitance

  • Grid-to-Plate Capacitance

    2.05 pF

    Section1

SECTION 2

Triode

Other

  • Plate Voltage

    90 V

    ClassA1

  • Grid Voltage

    -1 V

    ClassA1

  • Plate Current

    9 mA

    ClassA1

Capacitance

  • Grid-to-Plate Capacitance

    1.45 pF

    Section2