Pin-compatible Noval rectifier with higher current rating (150 mA vs 90 mA) — direct upgrade, but may affect B+ voltage due to lower internal resistance
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Max AC Voltage per Anode (RMS)350V
Heater-to-Cathode Voltage (max)Heater-to-Cathode Voltage (max)500V
Rectifier
Peak Inverse VoltagePeak Inverse Voltage1,000V
Voltage Drop (typical)Voltage Drop (per plate at 90 mA)17V
Max C-input Filter CapacitorMax C-input Filter Capacitor50µF
DC Output Current (max)DC Output Current (max)90mA
Peak Anode Current (surge)Peak Anode Current
Heater
Heater VoltageHeater Voltage6.3V
Heater CurrentHeater Current0.6A
Notes
A minimum series resistance (protecting resistance) per anode is mandatory to limit surge current when charging the input capacitor. Required values vary with transformer voltage: 125 ohm at 2x250 V, 175 ohm at 2x275 V, 215 ohm at 2x300 V, 300 ohm at 2x350 V.
Pins 2, 6, 8, and 9 are internal connections — do not ground or connect externally.
The EZ81 (6CA4) is pin-compatible but rated at 150 mA — a direct upgrade where more current headroom is needed.
DC output voltage with capacitor-input filter (CL=50 uF) at 90 mA: approximately 260 V at 2x250 Vrms, 285 V at 2x275 Vrms, 310 V at 2x300 Vrms, 360 V at 2x350 Vrms.