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

Voltage Triode Pentode ·Diode-Pentode-Triode

3A8GT

Directly heated diode-triode sharp-cutoff RF pentode combination for battery-operated receiving service.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
3
Base
8AS
Socket code
IO
Base pins
8
Nominal heater
2.8 V / 50 mA

Description

3A8GT is listed in the supplied receiving-tube handbook as a diode-triode sharp-cutoff RF pentode. The published heater/filament rating is 2.8 V at 0.05 A.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
8AS
Socket code
IO
Base pins
8
Nominal heater voltage
2.8 V
Nominal heater current
50 mA
Parallel heater voltage
1.4 V
Parallel heater current
100 mA
Series capable
Yes

8AS - Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

3 physical sections, each with unique specifications.

Section 1

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Published handbook ratings and operating characteristics reviewed.

Section 2

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
200000 Ω
Transconductance
0.000325 S
Amplification factor
65
Max plate voltage
110 V

Published handbook ratings and operating characteristics reviewed.

Section 3

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
800000 Ω
Transconductance
0.00075 S
Max plate voltage
110 V
Max screen voltage
110 V

Published handbook ratings and operating characteristics reviewed.

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 3

Pentode

Other

  • Maximum plate voltage

    110 V

    Published handbook rating

  • Maximum screen voltage

    110 V

    Published handbook rating

  • Plate voltage

    90 V

    ClassA

  • Screen voltage

    90 V

    ClassA

  • Control-grid bias

    0 V

    ClassA

  • Plate current

    1.5 mA

    ClassA

  • Screen current

    0.5 mA

    ClassA

Characteristic

  • Plate resistance

    800000 ohm

    Published handbook characteristic

  • Transconductance

    750 µS

    Published handbook characteristic

  • Heater/filament voltage

    2.8 V

    Published heater/filament rating

  • Heater/filament current

    50 mA

    Published heater/filament rating

Data set 02

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Diode

Characteristic

  • Minimum diode current

    0.5 mA

    10VDC

SECTION 2

Triode

Other

  • Triode plate voltage

    90 V

    Triode

Characteristic

  • Triode plate resistance

    200000 ohm

    Triode

  • Triode transconductance

    325 uS

    Triode

  • Triode amplification factor

    65

    Triode

SECTION 3

Pentode

Other

  • Pentode plate voltage

    90 V

    Pentode

  • Pentode screen voltage

    90 V

    Pentode

Characteristic

  • Pentode plate resistance

    800000 ohm

    Pentode

  • Pentode transconductance

    750 uS

    Pentode