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

7X7

Double-diode very-high-mu triode for detector, AVC, and voltage-amplifier service. Paired diode sections supply signal and control rectification while the triode provides substantial subsequent voltage gain.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
3
Base
8BZ
Socket code
-
Base pins
-
Nominal heater
7 V / 320 mA

Description

Twin diode–high-mu triode receiving tube.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
8BZ
Socket code
-
Base pins
-
Nominal heater voltage
7 V
Nominal heater current
320 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

8BZ - 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

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
67000 Ω
Transconductance
0.0015 S
Amplification factor
100
Max plate voltage
300 V

Values promoted only where clearly published for this section in the approved source.

Section 2

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Values promoted only where clearly published for this section in the approved source.

Section 3

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Values promoted only where clearly published for this section in the approved 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

1938 National Union

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

  • Diode #

    1 uuf

    Published source value; see source line context.

  • Diode #

    2 uuf

    Published source value; see source line context.

  • Diode Current per Plate with

    5 MA

    Published source value; see source line context.

  • Plate Current V@\fqqe

    100 Volts

    Published source value; see source line context.

  • Plzte Resistance

    85000 ohms

    Published source value; see source line context.

  • Plate Current

    1.2 MA

    Published source value; see source line context.

  • Caupling Capreiteance

    11 uuf

    Published source value; see source line context.

Other

  • Diode #

    2 uuf

    Published source value; see source line context.

  • Heater Voltage gAC or DC) (Nominal)

    7 Volts

    Published source value; see source line context.

  • Meximum Plate Voltage

    3155 Volts

    Published source value; see source line context.

  • Heat~r Voltage £€

    3 Volts

    Published source value; see source line context.

  • Grié Volteage ) r ~

    -1 Volts

    Published source value; see source line context.

  • Heater Voltage

    6.3 Volts

    Published source value; see source line context.

  • Plate Sunply Voltage

    1 Volts

    Published source value; see source line context.

  • Grid Lesk Following Stage

    10 megohm

    Published source value; see source line context.

  • Load Resistance

    2 megohm

    Published source value; see source line context.

  • Voltage Outpnut (RMS) at

    5 volts

    Published source value; see source line context.

Data set 02

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate voltage

    250 V

    ClassA

  • Grid voltage

    -1 V

    ClassA

  • Plate current

    1.9 mA

    ClassA

Characteristic

  • Plate resistance

    67000 ohm

    ClassA

  • Transconductance

    1500 uS

    ClassA

  • Amplification factor

    100

    ClassA