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Voltage - Triode (single) ·Triode

71A

Directly heated power-amplifier triode retained chiefly for replacement in older receivers; published audio output is below the project’s 5-watt power-category gate.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
4
Socket code
UX4
Base pins
4
Nominal heater
5 V / 250 mA

Description

Directly heated power-amplifier triode retained chiefly for replacement in older receivers. The French-language source has been translated to English.

Socket description

Medium-shell UX 4-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
4
Socket code
UX4
Base pins
4
Nominal heater voltage
5 V
Nominal heater current
250 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

4 - 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
1750 Ω
Transconductance
0.0017 S
Amplification factor
3
Max plate voltage
180 V

Published ratings and characteristics promoted from the approved datasheet.

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

1932 Cunningham Radio Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Grid-plate capacitance

    7.4 pF

    Published direct interelectrode capacitance

  • Grid-filament capacitance

    3.7 pF

    Published direct interelectrode capacitance

  • Plate-filament capacitance

    2.1 pF

    Published direct interelectrode capacitance

  • Load resistance

    3200 ohm

    Published operating characteristic

Data set 02

1937 Raytheon Radio Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate voltage

    80 V

    ClassA

  • Control-grid voltage

    -16.5 V

    ClassA

  • Plate current

    10 mA

    ClassA

  • Load resistance

    3000 Ω

    80VPlate

  • Power output

    125 mW

    80VPlate

  • Plate voltage

    135 V

    ClassA

  • Control-grid voltage

    -27 V

    ClassA

  • Plate current

    17.3 mA

    ClassA

  • Load resistance

    3000 Ω

    135VPlate

  • Power output

    400 mW

    135VPlate

  • Plate voltage

    180 V

    ClassA

  • Control-grid voltage

    -40.5 V

    ClassA

  • Plate current

    20 mA

    ClassA

  • Load resistance

    4800 Ω

    180VPlate

  • Power output

    790 mW

    180VPlate

Characteristic

  • Plate resistance

    2170 Ω

    80VPlate

  • Transconductance

    1400 µS

    80VPlate

  • Amplification factor

    3

    Section1

  • Plate resistance

    1820 Ω

    135VPlate

  • Transconductance

    1650 µS

    135VPlate

  • Plate resistance

    1750 Ω

    180VPlate

  • Transconductance

    1700 µS

    180VPlate

Data set 03

193X Cunningham

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

  • Heater/filament voltage

    5 V

    Published nominal

  • Heater/filament current

    250 mA

    Published nominal

  • Transconductance

    1650 uS

    Published characteristic

  • Amplification factor

    3

    Published characteristic

  • Plate resistance

    1820 Ohm

    Published characteristic

Data set 04

1940 RCA

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

  • Heater or filament voltage

    5 V

    Published nominal value

  • Heater or filament current

    250 mA

    Published nominal/aggregate value

  • Transconductance

    1700 µS

    Published operating characteristic

  • Amplification factor

    3

    Published operating characteristic

Other

  • Audio power output

    0.79 W

    180 V plate, published output-stage condition

Data set 05

1948 Brimar Radio Valve Manual

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

  • Anode Voltage

    180 V

  • Anode Current

    20 mA

  • Control Grid Voltage

    -40.5 V

  • Optimum Load

    4800 ohm

  • Power Output

    0.8 W

Data set 06

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

  • Heater Voltage

    5 V

  • Heater Current

    250 mA

Data set 07

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Voltage

    180 V

    ClassA

  • Power Output

    0.79 W

    ClassA

Characteristic

  • Plate Current

    20 mA

    ClassA

Capacitance

  • Grid To Plate Capacitance

    7.5 pF