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Voltage - Triode (single) ·Triode

247A

Western Electric general-purpose heater-cathode triode with published Class A operating data for signal and audio amplification.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
MEDIUM4BAYONET
Base pins
4
Nominal heater
2 V / 1.6 A

Description

Western Electric general-purpose triode with a 2.0 V, 1.6 A heater-type cathode and a published Class-A operating point.

Socket description

Medium 4-contact bayonet base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
MEDIUM4BAYONET
Base pins
4
Nominal heater voltage
2 V
Nominal heater current
1.6 A
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

1 physical section, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
16000 Ω
Transconductance
0.00094 S
Amplification factor
14.6
Max plate voltage
200 V
Max plate dissipation
1 W

Promoted fields mapped from published ratings/characteristics; additional published values preserved in parameter table.

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

1933 Western Electric Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate-grid capacitance

    3.2 pF

    Published direct interelectrode capacitance

  • Plate-cathode capacitance

    2.7 pF

    Published direct interelectrode capacitance

  • Grid-cathode capacitance

    4 pF

    Published direct interelectrode capacitance

Data set 02

1956 Western Electric Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Heater Voltage

    2 V

  • Heater Current

    1.6 A

  • Maximum Plate Voltage

    200 V

  • Maximum Plate Dissipation

    1 W

  • Maximum Heater-Cathode Voltage

    100 V

  • Plate Voltage

    135 V

    ClassA

  • Plate Current

    3.2 mA

    ClassA

  • Power Output

    0.037 W

    ClassA

Characteristic

  • Amplification Factor

    15.2

    ClassA

  • Transconductance

    940 µS

    ClassA

  • Plate Resistance

    16000 ohm

    ClassA

Data set 03

2026 Western Electric 200s

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

  • Heater Voltage

    2 Volt

    Heater Voltage 2 Volts, AC or DC

  • Plate Voltage

    1 Volt

    Plate Voltage 1 3 . 5 1 8 0 Vo l t s

  • Average Plate Resistance

    16200 Ohms

    Average Plate Resistance.... 16,200 16,000 Ohms

  • Average Amplification Factor

    14.9

    Average Amplification Factor 14.9 14.6

  • Heater voltage

    2 volt

    Heater voltage 2.0 volts, a.c. or d.c.

  • Nominal heater current

    1.6 amperes

    Nominal heater current 1.6 amperes

  • within the area, ABCD, in Figure

    3

    within the area, ABCD, in Figure 3. Amplification factor, plate resistance, transconductance, and

  • Microphonic and Sputter Noise—With a plate voltage of

    135 volt

    Microphonic and Sputter Noise—With a plate voltage of 135 volts, a grid bias of —4.5 volts,

  • and a load resistance of

    100000 ohms

    and a load resistance of 100,000 ohms, the mean microphonic noise output level of the 247A tube,

  • HEATER VOLTAGE =

    2 VOLT

    HEATER VOLTAGE = 2.0VOLTS