X21

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: 1
Base: -
Socket code: B7
Base pins: 7
Nominal heater: 2 V / 100 mA

Description

A variable-mu heptode electron-coupled frequency changer for 2-volt battery superheterodyne circuits, designed for satisfactory conversion conductance with low H.T. current.

Socket description

Medium 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: B7
Base pins: 7
Nominal heater voltage: 2 V
Nominal heater current: 100 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

1 physical section, each with unique specifications.

Section 1

Heptode

X-ray radiationInterelectrode capacitances

Transconductance: 0.00024 S
Max plate voltage: 150 V
Max screen voltage: 70 V

Published ratings and characteristics promoted from the approved datasheet.

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

1937 Osram Valves

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

Heater Voltage
2 V
Published datasheet value
Heater Current
100 mA
Published datasheet value
Anode Voltage Maximum
150 V
Published datasheet value
Screen Voltage Maximum
70 V
Published datasheet value
Oscillator Anode Voltage
90 V
Published datasheet value

Characteristic

Conversion Conductance
240 µS
Published datasheet value