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Voltage Radio Detector Converter ·Heptode

6D8G

Low-heater-current pentagrid oscillator-converter for superheterodyne receivers. Its multi-grid structure combines local oscillation and mixing while reducing heater-power demand compared with many contemporary converter tubes.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
8A
Socket code
IO
Base pins
8
Nominal heater
6.3 V / 150 mA

Description

Low-heater-current pentagrid converter with characteristics similar to the 6A7/6A8G family, intended for conventional converter service.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
8A
Socket code
IO
Base pins
8
Nominal heater voltage
6.3 V
Nominal heater current
150 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

8A - 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
400000 Ω
Max plate voltage
300 V
Max screen voltage
100 V
Max plate dissipation
1 W
Max cathode current
13 mA

Pentagrid converter for oscillator-mixer service.

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

1937 Raytheon Radio Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

  • SMALL Max, Plate Voltage

    250 V

    Published table

Capacitance

  • Grid #4 to all other Elements (R~F input)

    8.8 pF

    Published table

  • Grid #1 to all other Elements {Ose, input)

    6

    Published table

  • Grid #2 to all other Elements (

    0 pF

    Published table; Column1

  • Grid #2 to all other Elements (

    5 pF

    Published table; Column2

  • Plate to all other Elements (Mixer output)

    11 pF

    Published table

  • Plate Voltage

    138 V

    Published table; Column1

  • Plate Voltage

    250 V

    Published table; Column2

  • Conversion Transconductance

    325

    Published table; Column1

  • Conversion Transconductance

    500

    Published table; Column2

  • Plate Current

    1.2 mA

    Published table; Column1

  • Plate Current

    3.3 mA

    Published table; Column2

  • Control Grid Bias

    25 V

    Published table; Column1

  • Control Grid Bias

    38.5 V

    Published table; Column2

  • (For Conversion Transconductance =

    10 uS

    Published table

  • Grid #1 to Grid #2 Transconductance

    1

    Published table; Column1

  • Grid #1 to Grid #2 Transconductance

    1000

    Published table; Column2

Data set 02

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Heptode

Characteristic

  • Conversion Conductance

    500 µS

    250 V plate condition

Other

  • Plate Current

    3 mA

    250 V plate

  • Screen Current

    3.5 mA

    250 V plate

  • Oscillator Grid Current

    0.7 mA

    250 V plate

Capacitance

  • RF Input Capacitance

    7 pF

  • Mixer Output Capacitance

    9 pF

Data set 03

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

  • Plate voltage

    250 V

    Converter; OscillatorPlate250VThrough20000Ohm; OscillatorGridLeak50000Ohm; OscillatorCathodeCurrent0.4mA; TriodeOscillatorCurrent4.3mA

  • Screen voltage

    100 V

    Converter; OscillatorPlate250VThrough20000Ohm; OscillatorGridLeak50000Ohm; OscillatorCathodeCurrent0.4mA; TriodeOscillatorCurrent4.3mA

  • Control-grid bias magnitude

    3 V

    Converter; OscillatorPlate250VThrough20000Ohm; OscillatorGridLeak50000Ohm; OscillatorCathodeCurrent0.4mA; TriodeOscillatorCurrent4.3mA

  • Plate current

    3.5 mA

    Converter; OscillatorPlate250VThrough20000Ohm; OscillatorGridLeak50000Ohm; OscillatorCathodeCurrent0.4mA; TriodeOscillatorCurrent4.3mA

  • Screen current

    2.6 mA

    Converter; OscillatorPlate250VThrough20000Ohm; OscillatorGridLeak50000Ohm; OscillatorCathodeCurrent0.4mA; TriodeOscillatorCurrent4.3mA

  • Plate resistance

    400000 ohm

    Converter; OscillatorPlate250VThrough20000Ohm; OscillatorGridLeak50000Ohm; OscillatorCathodeCurrent0.4mA; TriodeOscillatorCurrent4.3mA

  • Transconductance

    550 uS

    Converter; OscillatorPlate250VThrough20000Ohm; OscillatorGridLeak50000Ohm; OscillatorCathodeCurrent0.4mA; TriodeOscillatorCurrent4.3mA

  • Oscillator cathode current

    0.4 mA

    Converter

  • Oscillator grid-leak resistance

    50000 ohm

    Converter

Data set 04

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Heptode

Characteristic

  • Plate Current

    3.5 mA

    Published operating/characteristic table

  • Screen Current

    2.6 mA

    Published operating/characteristic table