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

X719

Radio receiver frequency changer designed for superheterodyne mixer and oscillator service. Its multi-grid construction performs signal conversion, often integrating local oscillation and mixing within one valve.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
-
Socket code
B9A
Base pins
9
Nominal heater
6.3 V / 300 mA

Description

Triode-heptode frequency changer.

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
9
Nominal heater voltage
6.3 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

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances
Transconductance
0.0037 S
Amplification factor
22
Max plate voltage
250 V

Marconi X719/ECH81 oscillator triode of a 6.3 V 0.30 A indirectly heated triode-heptode receiver frequency changer. Manufacturer typical static triode characteristics at 100 V anode, zero grid bias: gm 3.7 mA/V, amplification factor 22. Oscillator-mode effective slope differs from intrinsic static gm and must not be substituted for it. B9A nine-pin base.

Section 2

Heptode

X-ray radiationInterelectrode capacitances
Max plate voltage
300 V
Max screen voltage
125 V
Max plate dissipation
1.7 W
Max screen dissipation
1 W
Max cathode current
12.5 mA

Marconi X719/ECH81 heptode frequency-converter and RF/IF amplifier section; 6.3 V, 0.30 A heater. Maximum anode voltage 300 V, screen voltage 125 V, plate dissipation 1.7 W, screen dissipation 1 W, cathode current 12.5 mA. The 250 V anode and 100 V screen values commonly used are typical circuit operating conditions, not maximum limits. Conversion conductance and RF/IF amplification slope are distinct operating-mode characteristics.

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

1955 Marconi

Published operating points and test conditions from this source.

SECTION 1

Triode

Application

  • Oscillator section function

    Local oscillator

Other

  • Oscillator anode voltage

    250 V

SECTION 2

Heptode

Construction

  • Mixer section identity

    Heptode

Other

  • Mixer anode voltage

    250 V

  • Mixer screen voltage

    100 V

Application

  • Frequency-changer service

    Explicit