Same UX4 base and filament (7.5V/1.25A) transmitting triode with identical physical dimensions but much higher mu (25 vs 3) and higher ra (9600 vs 2500 Ohm); designed for RF/oscillator service rather than AF power
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Plate Voltage (max)425V
Anode Dissipation (max)Plate Dissipation (max)12W
Cathode Current (max)Plate Current (max)60mA
Max Grid ResistorMax Grid Resistor (self-bias)1MΩ
Typical Operating
Notes
DHT tube: the thoriated tungsten filament serves as the cathode; there is no heater-cathode isolation.
Maximum plate current is 60 mA. Maximum plate dissipation is 12W.
Class A at Va=350V: Vg=-72V, peak grid swing=67V, Ia=34mA, gm=1.25 mA/V, ra=2400 Ohm, rl=5000 Ohm, Po=2.1W.
Class A at Va=425V: Vg=-100V, peak grid swing=95V, Ia=28mA, gm=1.2 mA/V, ra=2500 Ohm, rl=8000 Ohm, Po=3.0W.
Grid-voltage values on the datasheet are referenced to the filament midpoint (AC operation). For DC filament, decrease grid voltage by 5.0V and reference to the negative filament terminal.
For resistance-coupled circuits with self-bias, Rg_max is 1.0 Mohm. With fixed bias, grid-coupling resistance should not exceed 0.25 Mohm.
Outline dimensions, tube symbol, and socket connections are the same as for the 841.
Pin Layout — UX4
1Filament
2Plate (Anode)
3Grid
4Filament
Socket-Compatible Tubes ⚠ Not electrically compatible