Similar mercury-vapor rectifier on UX4 base but rated for lower inverse voltage — not a drop-in at full ratings
872A
Similar mercury-vapor rectifier but higher current rating (1.25A avg vs 0.25A avg) — different size class
Electrical Specifications
Rectifier
Peak Inverse VoltagePeak Inverse Voltage (20-60 C)10,000V
Voltage Drop (typical)Peak Tube Voltage Drop15V
DC Output Current (max)Average Anode Current (max)250mA
Peak Anode Current (surge)Peak Anode Current2,000mA
Heater
Notes
The filament must be heated for at least 15 seconds before applying anode voltage to allow the mercury to vaporize and reach operating temperature. Failure to observe this warm-up time will damage the cathode coating.
Condensed-mercury temperature must be maintained between 20-80 degrees C for reliable operation. Below 20 C, the mercury vapor pressure is too low; above 80 C, arc-back risk increases. Forced-air cooling may be required.
Peak inverse anode voltage ratings vary with condensed-mercury temperature: 2500V max (20-80 C), 5000V max (20-70 C), 10000V max (20-60 C).
Average anode current: 0.25A max (20-70 C), 0.5A max at restricted temperature range. Peak current 2A max (20-80 C).
Filament: 2.5V at 5A. Peak tube voltage drop approximately 15V.
Shields and RF filter circuits should be provided if the 866A is subjected to extraneous high-frequency fields. Mercury vapor is susceptible to RF-induced breakdown.