Data set 01
2026 Genalex Rebrand
Published operating points and test conditions from this source.
SECTION 1
Triode
Characteristic
Transconductance
4500 to 6500 µS
Plate 250 V; grid -2 V
Plate Current
9 to 12 mA
Plate 250 V; grid -2 V
Voltage - Dual Triode (similar) ·Triode-Triode
B739
Miniature twin triode for low-frequency voltage amplification, co-designated 12AT7 and ECC81, providing two general-purpose amplifier sections.
Directly heatedCold cathodeCommon cathodeDissimilar
- Sections
- 2
- Base
- -
- Socket code
- B9A
- Base pins
- 9
- Nominal heater
- 6.3 V / 370 mA
Description
Miniature twin triode for low-frequency voltage amplification; co-designated 12AT7 and ECC81.
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
- 370 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
- Amplification factor
- 45
- Max plate voltage
- 330 V
- Max plate dissipation
- 3.25 W
- Max cathode current
- 18 mA
Representative section for two electrically identical sections.
Section 2
Triode
X-ray radiationInterelectrode capacitances
- Amplification factor
- 45
- Max plate voltage
- 330 V
- Max plate dissipation
- 3.25 W
- Max cathode current
- 18 mA
Second physical triode restored under current one-row-per-physical-section policy.
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.