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Voltage Radio Detector Converter ·Heptode

7B8

Receiver oscillator-converter combining local oscillation and signal mixing for superheterodyne frequency conversion. Its multi-grid structure integrates the front-end frequency-changing functions in one envelope.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
8X
Socket code
B8G
Base pins
8
Nominal heater
7 V / 320 mA

Description

A Lock-In heptode converter designed for frequency-converter service and broadly equivalent in function to the 6A8GT.

Socket description

Loctal 8-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
8X
Socket code
B8G
Base pins
8
Nominal heater voltage
7 V
Nominal heater current
320 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

8X - 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

Heptode

X-ray radiationInterelectrode capacitances
Plate resistance
360000 Ω
Transconductance
0.00055 S
Max plate voltage
300 V
Max screen voltage
100 V
Max plate dissipation
1.1 W
Max screen dissipation
1.5 W
Max grid dissipation
0.75 W
Max cathode current
14 mA

Published promoted fields populated by semantic heading; identical repeated physical sections compressed.

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

1948 Brimar Radio Valve Manual

Published operating points and test conditions from this source.

SECTION 1

Heptode

Characteristics

  • Anode Voltage

    250 V

  • Anode Current

    3.5 mA

  • Screen Voltage

    100 V

    G3,G5

  • Screen Current

    2.7 mA

  • Oscillator Anode Voltage

    150 V

    G2

  • Oscillator Anode Current

    4 mA

  • Control Grid Voltage

    -3 V

    G4

  • Cathode Bias Resistor

    300 ohm

  • Oscillator Grid Resistor

    50000 ohm

    G1

  • Oscillator Grid Current

    0.4 mA

  • Conversion Conductance

    550 uS

Data set 02

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

  • HeaterVoltageNominal

    7 V

    Nominal

  • HeaterCurrentNominal

    320 mA

    Nominal

  • Plate Voltage

    250 V

    Converter

  • Screen Voltage

    100 V

    Converter

Characteristic

  • Conversion Conductance

    350 uS

    PlateVoltage=250V

Data set 03

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

  • Oscillator-grid current

    0.4 mA

    Converter

  • Oscillator-grid resistor

    50000 Ohm

    Converter

  • Typical plate voltage

    250 V

    Converter

  • Typical screen voltage

    100 V

    Converter

  • Typical grid voltage

    -3 V

    Converter

  • Typical plate current

    3.5 mA

    Converter

  • Typical screen current

    2.7 mA

    Converter

  • Oscillator plate voltage

    250 V

    Converter

  • Oscillator plate series resistance

    20000 Ohm

    Converter

  • Oscillator plate current

    4 mA

    Converter

Characteristic

  • Plate resistance

    360000 Ohm

    Converter

  • Conversion transconductance

    550 uS

    Converter

Data set 04

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Heptode

Characteristic

  • Conversion Transconductance

    550 uS

    Typical

  • Oscillator Transconductance

    1150 uS

    OscillatorNotOscillating