Data set 01
1956 Western Electric Tubes
Published operating points and test conditions from this source.
SECTION 1
Triode
Characteristic
HeaterOrFilamentVoltage
7.5 V
HeaterOrFilamentCurrent
1.25 A
Voltage - Triode (single) ·Triode
281A
General-purpose receiving triode for voltage amplification, detection, oscillator, or Class-A service as documented by the manufacturer.
Directly heatedCold cathodeCommon cathodeDissimilar
- Sections
- 1
- Base
- -
- Socket code
- MEDIUM5
- Base pins
- 5
- Nominal heater
- 7.5 V / 1.25 A
Description
General-purpose directly heated triode from the Western Electric table.
Socket description
Medium 5-contact transmitting-tube base
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- -
- Socket code
- MEDIUM5
- Base pins
- 5
- Nominal heater voltage
- 7.5 V
- Nominal heater current
- 1.25 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
- 3600 Ω
- Amplification factor
- 5.2
- Max plate voltage
- 250 V
- Max cathode current
- 45 mA
Representative maximum operating-point values; OCR omits numeric limiting-condition values, so unsupported maxima not inferred.
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 200s
Published operating points and test conditions from this source.
SECTION 1
Triode
Capacitance
ControlGridToPlateCapacitance
3.8 pF
ControlGridToFilamentPositiveGridCapacitance
18 pF
PlateToFilamentPositiveGridCapacitance
9.4 pF