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Voltage - Triode (with diode, heptode or hexode) ·Diode-Diode-Diode-Triode

9AK8

Three-diode/triode combination developed for television and receiver signal detection and audio amplification. Three diode sections accommodate detector and demodulator functions while the high-mu triode provides subsequent voltage gain.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
4
Base
-
Socket code
B9A
Base pins
-
Nominal heater
9.5 V / 300 mA

Description

The Ferranti 9AK8 combines three diode detector/demodulator sections with a triode for AF amplification in FM/AM receivers.

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
-
Socket code
B9A
Base pins
-
Nominal heater voltage
9.5 V
Nominal heater current
300 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

4 physical sections, each with unique specifications.

Section 1

Diode

X-ray radiationInterelectrode capacitances
Rectifier peak inverse voltage
350 V
Rectifier nominal output current
10 mA
Rectifier peak forward current
75 mA

Published ratings/characteristics promoted where clearly stated; repeated identical sections compressed where applicable.

Section 2

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Published ratings and characteristics promoted from the supplied Rogers/Rogers Majestic source.

Section 3

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Published ratings and characteristics promoted from the supplied Rogers/Rogers Majestic source.

Section 4

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
50000 Ω
Transconductance
0.0014 S
Amplification factor
70
Max plate voltage
300 V
Max plate dissipation
1 W
Max cathode current
5 mA

Published ratings and characteristics promoted from the supplied Rogers/Rogers Majestic source.

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

1953 RFT Rundfunk Technik

Published operating points and test conditions from this source.

SECTION 1

Diode

Characteristics

  • Heater voltage

    9.5 V

    Published nominal value

  • Heater current

    300 mA

    Published nominal value

  • Transconductance

    1500 µS

    Published operating characteristic

SECTION 4

Triode

Other

  • HeaterVoltageNominal

    6.3 V

    Nominal

  • HeaterCurrentNominal

    450 mA

    Nominal

  • Maximum Plate Voltage

    300 V

  • Maximum Plate Dissipation

    1 W

Data set 02

1959 Rogers

Published operating points and test conditions from this source.

SECTION 1

Diode

Characteristic

  • HeaterOrFilamentVoltage

    9.5 V

  • HeaterOrFilamentCurrent

    300 mA

SECTION 4

Triode

Characteristic

  • Application

    Video and audio signal detection

    Television

Data set 03

1961 Ferranti Technical Handbook

Published operating points and test conditions from this source.

SECTION 1

Diode

Other

  • Peak Inverse Voltage

    350 V

    Each diode

  • Peak Current Diode 1

    6 mA

  • Peak Current Diode 2

    75 mA

  • Peak Current Diode 3

    75 mA

SECTION 4

Triode

Characteristics

  • Plate Voltage

    200 V

  • Plate Current

    1 mA

  • Transconductance

    1400 uS

  • Plate Resistance

    50000 ohm

  • Amplification Factor

    70 ratio

Other

  • Stage Gain

    53 ratio

    AFAmplifier