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Power - Triode ·Triode-Triode

4074A

Dual power triode for both audio and RF applications. Its paired sections support push-pull Class B or paralleled Class A audio operation, while reduced-rating RF service extends into the UHF region near 300 MHz.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
-
Socket code
MEDIUM7
Base pins
7
Nominal heater
6.3 V / 800 mA

Description

4074A is a double triode; both sections identical; one representative section emitted. The Standard Valves sheet publishes construction, electrical constants, limiting conditions, and applicable operating data.

Socket description

Medium 7-contact transmitting-tube base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
MEDIUM7
Base pins
7
Nominal heater voltage
6.3 V
Nominal heater current
800 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
4700 Ω
Transconductance
0.0029787234042553193 S
Amplification factor
14
Max plate voltage
300 V
Max plate dissipation
5 W
Max cathode current
50 mA

Representative row for two electrically identical triode sections.

Section 2

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
4700 Ω
Transconductance
0.0029787234042553193 S
Amplification factor
14
Max plate voltage
300 V
Max plate dissipation
5 W
Max cathode current
50 mA

Identical second physical section; duplicated from representative section per physical-section-row policy.

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 Standard Valves

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Maximum anode current

    50 mA

    OneSection

  • Nominal power output

    0.8 W

    ClassA;TwoSectionsParallel

  • Power output

    12 W

    ClassB;PushPull;TwoSections

Data set 02

1946 Standard Telephone and Cables

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Grid-anode capacitance

    2.7 pF

    Published capacitance

  • Grid-cathode capacitance

    6 pF

    Published capacitance

  • Anode-cathode capacitance

    2.1 pF

    Published capacitance

Data set 03

1947 Standard Valves

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Maximum frequency at full ratings

    100 MHz

  • Maximum operating frequency

    300 MHz

  • RF power output

    14 W