Contemporary DHT triode on UX4 base with 5V filament, similar mu (8) but higher ra (15000 Ω) and lower gm — used in similar applications but different operating characteristics
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Max Plate Voltage180V
Typical Operating
Anode Voltage (typical)Plate Voltage135V
Grid 1 Bias VoltageGrid Voltage-9V
Anode CurrentPlate Current6.2mA
Anode ResistancePlate Resistance
Heater
Heater VoltageFilament Voltage (DC)5V
Heater CurrentFilament Current0.25A
Notes
One of the earliest oxide-coated filament triodes, introduced in the mid-1920s. The 112A superseded the original type 112 with improved characteristics.
The UX prefix denotes the UX4 base; later manufacturing dropped the prefix, designating it simply as 112A or 12A.
Cunningham marketed the same tube as CX-112-A.
Filament may be operated from a 6V storage battery with a suitable series resistor to reduce voltage to 5.0V at the socket terminals.
As a detector: recommended plate voltage 45V with grid leak and condenser bias. Grid leak 0.25 to 5 MΩ with 0.00025 µF grid condenser.
As an amplifier at Va=135V: Pout=115 mW into 8700 Ω load. At Va=180V (max): Pout=260 mW into 10800 Ω load.
When substituted for the 01A in radio-frequency circuits, neutralizing condensers or grid suppressor resistors may need adjustment to prevent oscillation.
Pin Layout — UX4
1Filament (f+)
2Plate
3Grid
4Filament (f-)
Socket-Compatible Tubes ⚠ Not electrically compatible