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Voltage Pentode or Tetrode (under 100V) ·Heptode

1R5

Widely used battery pentagrid converter for portable superheterodyne receivers. It combines local oscillator and mixer functions while its economical filament and modest supply requirements suit compact battery radios.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: 7AT
Socket code: B7G
Base pins: 7
Nominal heater: 1.4 V / 50 mA

Description

Directly heated heptode frequency converter for battery radio receivers.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 7AT
Socket code: B7G
Base pins: 7
Nominal heater voltage: 1.4 V
Nominal heater current: 50 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

7AT - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1G5	A	G5 — Fifth GridGroup 7AT1 Original EIA source label G5; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN1F	—	F — FilamentGroup 7AT1 Original EIA source label F; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN2P	A	P — Plate (Anode) Original EIA source label P; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN3G2	A	G2 — Screen GridGroup 7AT3 Original EIA source label G2; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN3G4	A	G4 — Fourth GridGroup 7AT3 Original EIA source label G4; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN4G1	A	G1 — Control Grid Original EIA source label G1; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN5G5	A	G5 — Fifth GridGroup 7AT5 Original EIA source label G5; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN5F	—	F — FilamentGroup 7AT5 Original EIA source label F; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN6G3	A	G3 — Suppressor Grid Original EIA source label G3; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT
PIN7F	—	F — Filament Original EIA source label F; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 128, 7AT

Section ratings

1 physical section, each with unique specifications.

Section 1

Heptode

X-ray radiationInterelectrode capacitances

Plate resistance: 400000 Ω
Transconductance: 0.00028 S
Amplification factor: 6.5
Max plate voltage: 90 V
Max screen voltage: 90 V
Max cathode current: 5.5 mA

Promoted gm/mu are oscillator characteristics; conversion transconductance preserved as parameter.

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

1948 Brimar Radio Valve Manual

Published operating points and test conditions from this source.

SECTION 1

Heptode

Characteristic

HeaterOrFilamentVoltage
1.4 V
HeaterOrFilamentCurrent
50 mA
Conversion Conductance
300 uS
PlateVoltage=90V;ScreenVoltage=67.5V

Data set 02

1958 Brimar Radio Valve No 7

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

Plate Voltage
90 V
Plate Current
1.6 mA
Screen Voltage
67.5 V
Screen Current
3.2 mA

Characteristic

Plate Resistance
600000 ohm
Conversion Conductance
300 µS
Operating Frequency Maximum
20 MHz

Data set 03

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

Plate voltage
90 V
ClassA; OperatingPoint1
Screen voltage
67.5 V
ClassA; OperatingPoint1
Control-grid bias
0 V
ClassA; OperatingPoint1
Plate current
1.5 mA
ClassA; OperatingPoint1
Screen current
3.5 mA
ClassA; OperatingPoint1
Plate voltage
45 V
ClassA; OperatingPoint2
Screen voltage
45 V
ClassA; OperatingPoint2
Control-grid bias
0 V
ClassA; OperatingPoint2
Plate current
0.7 mA
ClassA; OperatingPoint2
Screen current
2.1 mA
ClassA; OperatingPoint2
Oscillator grid current
0.25 mA
Vp=90 V; Screen=67.5 V
Oscillator grid resistor
100000 ohm
Vp=90 V; Screen=67.5 V

Data set 04

1961 Ferranti Technical Handbook

Published operating points and test conditions from this source.

SECTION 1

Heptode

Characteristic

HeaterOrFilamentVoltage
1.4 V
HeaterOrFilamentCurrent
50 mA
MaximumOperatingFrequency
20 MHz
FrequencyChanger

Data set 05

1966 Tung Sol Electronic Tubes 1 of 4

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

Plate voltage
90 V
Converter
Screen voltage
67.5 V
Converter
Plate current
1.3 mA
Converter
Screen current
2.4 mA
Converter
Application
Pentagrid converter/oscillator-mixer for battery receivers
Section1

Characteristic

Conversion transconductance
325 µS
Converter
Plate resistance
0.4 MΩ
Converter

Data set 06

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

Plate voltage
45 V
ConverterService;OperatingPoint1
Screen voltage
45 V
ConverterService;OperatingPoint1
Plate current
0.7 mA
ConverterService;OperatingPoint1
Screen current
2.1 mA
ConverterService;OperatingPoint1
Plate voltage
67.5 V
ConverterService;OperatingPoint2
Screen voltage
67.5 V
ConverterService;OperatingPoint2
Plate current
1.4 mA
ConverterService;OperatingPoint2
Screen current
3.5 mA
ConverterService;OperatingPoint2
Plate voltage
90 V
ConverterService;OperatingPoint3
Screen voltage
67.5 V
ConverterService;OperatingPoint3
Plate current
1.5 mA
ConverterService;OperatingPoint3
Screen current
3.5 mA
ConverterService;OperatingPoint3

Characteristic

Plate resistance
500000 ohm
ConverterService;OperatingPoint1
Conversion transconductance
210 uS
ConverterService;OperatingPoint1
Plate resistance
400000 ohm
ConverterService;OperatingPoint2
Conversion transconductance
280 uS
ConverterService;OperatingPoint2
Plate resistance
400000 ohm
ConverterService;OperatingPoint3
Conversion transconductance
280 uS
ConverterService;OperatingPoint3
Oscillator transconductance
1400 uS
OscillatorNotOscillating
Oscillator amplification factor
6.5
OscillatorNotOscillating

Data set 07

1968 Mazda Belvu

Published operating points and test conditions from this source.

SECTION 1

Heptode

Characteristics

Heater or filament voltage
1.4 V
Published nominal value
Heater or filament current
50 mA
Published nominal value
Conversion transconductance
280 µA/V
67.5 V operating condition