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Rectifier - TV Line Scan Boost ·Rectifier

1AU3

High-voltage television flyback/EHT rectifier designed to convert horizontal-output transformer pulses into the DC accelerating supply required by the CRT.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
3C
Socket code
OCTAL7
Base pins
7
Nominal heater
1.25 V / 200 mA

Description

1AU3 — Filamentary Half-Wave Diode

The 1AU3 is a filamentary half-wave diode incorporating an electrostatic shield adjacent to the filament. It is designed primarily for use as a high-voltage rectifier in television receivers and other high-voltage rectifier applications.

Mechanical Construction and Pinout

The 1AU3 features a T-12 glass bulb envelope and is constructed with a coated filament cathode. It utilizes a short medium shell octal 7-pin base (designated as 3C) and can be mounted in any position.

Physical Dimensions

  • Maximum Diameter: 1-9/16"
  • Maximum Overall Length: 3-7/8"
  • Maximum Seated Height: 3-5/16"

Pin Connections and Socket Guidelines

The electrical connections are accessed via the 7-pin base and a top cap. The bottom-view pinout is configured as follows:

PinConnection
Pin 1IC (Internal Connection)
Pin 2F (Filament)
Pin 3IC (Internal Connection)
Pin 4IC (Internal Connection)
Pin 5IC (Internal Connection)
Pin 6NC / IC (No Connection / Internal Connection)
Pin 7F, S (Filament, Shield)
Pin 8IC (Internal Connection)
Top CapP (Plate)

Specific socket wiring guidelines must be followed when integrating the 1AU3 into a circuit:

  • Socket terminals 1, 3, 4, 5, 6, and 8 may be connected directly to terminal 7 or to an external corona shield that is connected to terminal 7.
  • Terminals 4 and 6 are permitted for use as tie points for auxiliary components that operate at or near filament potential.

Filament and Electrical Characteristics

The 1AU3 is designed with a coated filament cathode. To ensure reliable operation, the filament supply must be carefully regulated.

ParameterValue
Nominal (Bogey) Filament Voltage1.25 V
Filament Voltage Tolerance± 0.2 V
Filament Current (at 1.25 V)0.20 A
Direct Interelectrode Capacitance (Plate to Filament and Shield)2.0 pF
Approximate Tube Drop (at 7 mA plate current)225 V

Filament Supply Design Guidelines

Equipment utilizing the 1AU3 must be designed so that the filament voltage is centered at the specified bogey value of 1.25 V. Circuit variations must be strictly restricted to maintain the operating voltage within the specified ± 0.2 V tolerance.

Design-Maximum Ratings and Operating Conditions

The ratings for the 1AU3 are established under the Design-Maximum System. These limits represent the maximum electrical boundaries for safe and reliable operation in flyback voltage rectifier service.

Rating ParameterMaximum Limit
Maximum Inverse Plate Voltage (Total DC and Peak)30,000 V
Maximum Inverse Plate Voltage (DC)26,000 V
Maximum Peak Plate Current50 mA
Maximum Average Plate Current0.5 mA

Pulse Duty Cycle

When operated in a standard television scanning system (specifically a 525-line, 30-frame system), the duty cycle of the high-voltage pulse must not exceed 15% of one scanning cycle.

Safety and X-Ray Radiation Warning

When the 1AU3 is operated at potentials higher than 16,000 volts, it can produce X-ray radiation. To protect against the possible danger of personal injury from prolonged exposure at close range, the installation of an appropriate X-ray radiation shield may be necessary.

Socket description

7-contact octal-family base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
3C
Socket code
OCTAL7
Base pins
7
Nominal heater voltage
1.25 V
Nominal heater current
200 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

3C - Terminal pinout

Electrical assignments shared by every tube using this base designation.

TerminalSectionConnectionEvidence
PIN1Pin 1—IC

Transcribed directly from EIA chart; independent cross-check not yet performed.

Unverified

EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3C

PIN2Pin 2—F — Filament

Transcribed directly from EIA chart; independent cross-check not yet performed.

Unverified

EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3C

PIN3Pin 3—IC

Transcribed directly from EIA chart; independent cross-check not yet performed.

Unverified

EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3C

PIN5Pin 5—IC

Transcribed directly from EIA chart; independent cross-check not yet performed.

Unverified

EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3C

PIN7Pin 7—F — Filament

Transcribed directly from EIA chart; independent cross-check not yet performed.

Unverified

EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3C

PIN8Pin 8—IC

Transcribed directly from EIA chart; independent cross-check not yet performed.

Unverified

EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3C

CAP1Top capAP — Plate (Anode)

Transcribed directly from EIA chart; independent cross-check not yet performed.

Unverified

EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3C

Section ratings

1 physical section, each with unique specifications.

Section 1

Rectifier

X-ray radiationInterelectrode capacitances
Max cathode current
0.5 mA
Rectifier peak inverse voltage
30000 V
Rectifier nominal output current
0.5 mA
Rectifier peak forward current
50 mA
Rectifier forward voltage drop
225 V

Primary promoted rectifier values from flyback-voltage rectifier ratings.

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

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Rectifier

Other

  • Filament Voltage

    1.25 V

    Nominal

  • Filament Current

    200 mA

    Nominal

  • InversePlateVoltageTotalDcAndPeak

    30000 V

    FlybackVoltageRectifier

  • InversePlateVoltageDc

    26000 V

    FlybackVoltageRectifier

  • Peak Plate Current

    50 mA

    FlybackVoltageRectifier

  • Average Plate Current

    0.5 mA

    FlybackVoltageRectifier

  • FlybackPulseDutyCycle

    15 %

    525Line30FrameTV;NotToExceed

Capacitance

  • Plate To Filament And Internal Shield Capacitance

    2 pF

Characteristic

  • Tube Voltage Drop

    225 V

    PlateCurrent=7mA;Approx

Data set 02

1966 Tung Sol Electronic Tubes 1 of 4

Published operating points and test conditions from this source.

SECTION 1

Rectifier

Other

  • Filament/heater voltage

    1.25 V

  • Filament/heater current

    200 mA

  • Maximum total DC-plus-peak inverse voltage

    - to 30000 V

    FlybackRectifier

  • Maximum steady-state peak plate current

    50 mA

    FlybackRectifier

  • Maximum DC output current

    0.5 mA

    FlybackRectifier

Capacitance

  • Plate-to-filament/heater capacitance

    2 pF

    Approximate