Smaller half-wave mercury-vapor rectifier (250 mA avg, 5000 V PIV); same Jumbo 4-pin bayonet base family
Electrical Specifications
Rectifier
Peak Inverse VoltagePeak Inverse Anode Voltage (max, 20-60°C)10,000V
Voltage Drop (typical)Peak Tube Voltage Drop (approx)10V
Peak Anode Current (surge)Peak Anode Current (max)5,000mA
Max DC Output Current (total, not per-anode)Max DC Output Current1,250mA
Heater
Notes
Mercury-vapor tube — must be operated within a condensed-mercury temperature range of 20°C to 60°C for full 10 kV PIV rating. At 20°C to 70°C range, PIV is derated to 5000 V.
Operation at 40°C +/- 5°C is recommended for optimal performance.
Filament must be applied for at least 30 seconds before applying anode voltage to allow mercury vapor pressure to stabilize.
Filament voltage range: 4.75 to 5.25 V. Average filament current is 7.5 A, maximum 8 A.
Peak tube voltage drop is approximately 10 V — very low and essentially constant across the operating current range, which is the key advantage of mercury-vapor rectifiers.
Uses Medium-Metal-Shell Jumbo 4-Pin Bayonet Base (JETEC No.A4-29) with medium top cap (JETEC No.C1-5). Not interchangeable with UX4-based tubes.
T-18 bulb envelope. Total weight approximately 7 oz.
Shields and RF filter circuits should be provided if subjected to extraneous high-frequency fields, as these can cause breakdown effects in mercury vapor.
Fault current for 0.1 second duration: 50 mA max (at 20-70°C range). This limits the tube's ability to survive short-circuit conditions.
The 872 (without 'A' suffix) is an earlier version with different ratings — not a direct equivalent.
In half-wave single-phase service (Fig. 1 in datasheet): max transformer secondary 7000 V RMS (at 20-40°C) or 5500 V RMS (at 20-60°C), approx DC output 3200/1600 V at 1.25 A.