12SA7GT

GT-envelope heptode frequency converter for superheterodyne receivers. Local-oscillator and mixer functions are integrated in one tube, with heater characteristics suited to AC/DC series-string radio designs.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: 8AD
Socket code: IO
Base pins: 8
Nominal heater: 12.6 V / 150 mA

Description

GT-envelope pentagrid converter for frequency-conversion service.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 8AD
Socket code: IO
Base pins: 8
Nominal heater voltage: 12.6 V
Nominal heater current: 150 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

8AD - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1IS	A	IS — Internal Screen EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN2H	—	H — Heater EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN3P	A	P — Plate (Anode) EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN4G2	A	G2 — Screen GridGroup 8AD4 EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN4G4	A	G4 — Fourth GridGroup 8AD4 EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN5G1	A	G1 — Control Grid EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN6G5	A	G5 — Fifth GridGroup 8AD6 EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN6K	A	K — CathodeGroup 8AD6 EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN7H	—	H — Heater EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD
PIN8G3	A	G3 — Suppressor Grid EIA transcription; confirmation pending	Unverified EIA Base Connections, printed page 129, 8AD

Section ratings

1 physical section, each with unique specifications.

Section 1

Heptode

X-ray radiationInterelectrode capacitances

Plate resistance: 500000 Ω
Max plate voltage: 300 V
Max screen voltage: 100 V

Promoted from printed maximum/characteristic columns; additional published values retained in TUBE_SECTION_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

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

Oscillator-grid current
0.5 mA
Converter
Oscillator-grid resistor
20000 Ω
Converter
Plate voltage
100 V
Converter
Screen voltage
100 V
Converter
Control-grid voltage
-2 V
Converter
Plate current
3.3 mA
Converter
Screen current
8.5 mA
Converter

Characteristic

Plate resistance
500000 Ω
Converter
Conversion transconductance
425 µS
Converter