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Voltage Pentode or Tetrode (with diode) ·Diode-Diode-Pentode

8LT8

Series-string television diode-pentode intended for IF and video-detector service, combining wideband pentode amplification with a dedicated signal-detection diode.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
3
Base
9RL
Socket code
B9A
Base pins
9
Nominal heater
8.1 V / 450 mA

Description

Twin diode and sharp-cutoff pentode for television horizontal oscillator and AFC discriminator circuits.

Socket description

Small-button Noval 9-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
9RL
Socket code
B9A
Base pins
9
Nominal heater voltage
8.1 V
Nominal heater current
450 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

9RL - 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.

Representative of two diode sections.

Section 2

Diode

X-ray radiationInterelectrode capacitances
Max cathode current
5 mA

Second physical diode section added in approved reconciliation.

Section 3

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
200000 Ω
Transconductance
0.013 S
Max plate voltage
330 V
Max screen voltage
330 V
Max plate dissipation
3.1 W
Max screen dissipation
0.65 W

Published ratings and characteristics extracted from the approved RCA source. Pulse-only ratings remain parameter rows unless explicitly continuous.

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

1964 RMA EIA

Published operating points and test conditions from this source.

SECTION 1

Diode

Other

  • Maximum Continuous Diode Current

    5 mA

    EachDiode

Characteristics

  • Diode Plate-Cathode Capacitance

    1.4 pF

    Representative

SECTION 3

Pentode

Characteristics

  • Heater Voltage

    8.1 V

  • Heater Current

    450 mA

  • Heater Warm-up Time

    11 s

  • Plate-Grid Capacitance

    0.05 pF

  • Input Capacitance

    10 pF

  • Output Capacitance

    3.8 pF

  • Plate Voltage

    125 V

  • Screen Voltage

    125 V

  • Plate Resistance

    200000 ohm

  • Transconductance

    13000 uS

  • Plate Current

    10 mA

  • Screen Current

    3.4 mA

Other

  • Maximum Plate Voltage

    330 V

  • Maximum Screen Supply Voltage

    330 V

  • Maximum Plate Dissipation

    3.1 W

  • Maximum Screen Dissipation

    0.65 W

Data set 02

1975 RCA RC30

Published operating points and test conditions from this source.

SECTION 3

Pentode

Other

  • Heater Warm-up Time (Average)

    11 s

    Other;PublishedValue1

  • Heater Warm-up Time (Average)

    11 s

    Other;PublishedValue2

  • Heater Warm-up Time (Average)

    11 s

    Other;PublishedValue3

  • Peak value

    200 V

    Other;PublishedValue1

  • Peak value

    200 V

    Other;PublishedValue2

  • Peak value

    200 V

    Other;PublishedValue3

  • Average value

    100 V

    Other;PublishedValue1

  • Average value

    100 V

    Other;PublishedValue2

  • Average value

    100 V

    Other;PublishedValue3

  • Plate Voltage

    330 V

    MaximumRating

  • Grid-No

    2 V

    MaximumRating;PublishedValue1

  • Grid-No

    330 V

    MaximumRating;PublishedValue2

  • Grid-No.l (Control-Grid) Voltage, Positive-bias value

    0 V

    MaximumRating

  • Plate Dissipation

    3.1 W

    MaximumRating

  • For grid-No

    2 V

    MaximumRating;PublishedValue1

  • For grid-No

    165 V

    MaximumRating;PublishedValue2

  • For grid-No

    0.65 V

    MaximumRating;PublishedValue3

  • For grid-No

    2 V

    MaximumRating;PublishedValue1

  • For grid-No

    165 V

    MaximumRating;PublishedValue2

  • For grid-No

    33 V

    MaximumRating;PublishedValue3

  • For grid-No

    300 V

    MaximumRating;PublishedValue4

  • Maximum Plate Voltage

    330 V

    Section1

  • Maximum Screen Voltage

    330 V

    Section1

  • Maximum Plate Dissipation

    3.1 W

    Section1

  • Maximum Screen Dissipation

    0.65 W

    Section1

Characteristic

  • Plate Voltage

    125 V

    Characteristic

  • Grid-No

    2 V

    Characteristic;PublishedValue1

  • Grid-No

    125 V

    Characteristic;PublishedValue2

  • Cathode-Bias Resistor

    56 ohm

    Characteristic

  • Plate Resistance (Approx.)

    200000 ohm

    Characteristic

  • Plate Current

    10 mA

    Characteristic

  • Grid-No

    2 mA

    Characteristic;PublishedValue1

  • Grid-No

    3.4 mA

    Characteristic;PublishedValue2

  • Grid-No.l Voltage (Approx.) for plate current of

    20 V

    Characteristic;PublishedValue1

  • Grid-No.l Voltage (Approx.) for plate current of

    -3.5 V

    Characteristic;PublishedValue2

  • Tube Voltage Drop for plate current of

    20 mA

    Characteristic

  • Plate Resistance

    200000 ohm

    Section1

  • Transconductance

    13000 uS

    Section1