Data set 01
1956 Western Electric Tubes
Published operating points and test conditions from this source.
SECTION 1
Triode
Application
Tube service
Transmitting tube
Other
Typical RF power output
1500 W
Power - Triode (over 1000V 100W) ·Triode
331A
Western Electric thoriated-tungsten air-cooled transmitting triode for RF power service. Its 125 W plate dissipation, 1.5 kV plate rating, relatively high amplification factor, and low capacitances suit medium-power transmitters through roughly 30 MHz.
Directly heatedCold cathodeCommon cathodeDissimilar
- Sections
- 1
- Base
- -
- Socket code
- UX4
- Base pins
- 4
- Nominal heater
- 10 V / 8.25 A
Description
Air-cooled transmitting triode for RF power service.
Socket description
Medium-shell UX 4-contact
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- -
- Socket code
- UX4
- Base pins
- 4
- Nominal heater voltage
- 10 V
- Nominal heater current
- 8.25 A
- 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
Triode
X-ray radiationInterelectrode capacitances
- Plate resistance
- 8900 Ω
- Transconductance
- 0.0045 S
- Amplification factor
- 40
- Max plate voltage
- 1500 V
- Max plate dissipation
- 125 W
- Max cathode current
- 200 mA
Values extracted from Western Electric summary tables; additional table data retained as parameters.
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 02
2026 Western Electric 300s
Published operating points and test conditions from this source.
SECTION 1
Triode
Capacitance
Plate to grid
6.7 pF
Grid to filament
9 pF
Plate to filament
2.6 pF
Other
Maximum direct grid current
70 mA
Maximum RF grid current
5 A
Maximum frequency at full ratings
30 MHz
Approximate maximum output two tubes
370 W
ClassB;PushPull;PlateVoltage=1500V