{"type_number":"EZ81","canonical_url":"https://tubeofile.com/tubes/EZ81","manufacturer":null,"tube_type_key":"rectifier","tube_type_display_name":"Rectifier","base_name":"Noval","description":"Full-wave vacuum rectifier (twin diode) for power supply use in audio amplifiers and receivers. Indirectly heated, Noval base. Higher current rating than the EZ80, suitable for compact amplifier designs.","is_directly_heated":false,"completeness":"high","notes":["A minimum series resistance per anode of approximately 230 ohm is mandatory with capacitor-input filters to limit surge current when charging the input capacitor.","Some manufacturers label pins 2, 6, 8, and 9 as internal connections (IC) rather than no connection (NC). Check the specific manufacturer's datasheet before grounding or connecting these pins.","The EZ80 (6V4) is pin-compatible but rated at only 90 mA with a 0.6 A heater — not a drop-in replacement for the EZ81 in circuits drawing over 90 mA.","Voltage drop of approximately 20 V is sourced from community measurements and forum discussions, not from the manufacturer datasheet."],"references":["https://frank.pocnet.net/sheets/020/e/EZ81.pdf","https://frank.pocnet.net/sheets/030/e/EZ81.pdf"],"source_urls":{"r_type":"http://www.r-type.org/exhib/aai0030.htm","tdsl":"http://tdsl.duncanamps.com/show.php?des=EZ81","radiomuseum":"https://www.radiomuseum.org/tubes/tube_ez81.html"},"raw_equivalents":["6CA4","CV5072","U709","UU12"],"equivalents":[],"similar":[],"pins":[{"pin_number":"1","function":"Anode 1","function_code":"a1","notes":null},{"pin_number":"2","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"3","function":"Cathode","function_code":"k","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Heater","function_code":"h","notes":null},{"pin_number":"6","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"7","function":"Anode 2","function_code":"a2","notes":null},{"pin_number":"8","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"9","function":"No Connection","function_code":"nc","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"6.3","numeric_value":"6.3","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"1.0","numeric_value":"1","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Rectifier","tube_type_key":"rectifier","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"350","numeric_value":"350","unit":"V","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"500","numeric_value":"500","unit":"V","param_group":"absolute_max"},{"key":"PIV","display_name":"Peak Inverse Voltage","value":"1300","numeric_value":"1300","unit":"V","param_group":"rectifier"},{"key":"Vdrop","display_name":"Voltage Drop (typical)","value":"20","numeric_value":"20","unit":"V","param_group":"rectifier"},{"key":"C_max","display_name":"Max C-input Filter Capacitor","value":"50","numeric_value":"50","unit":"µF","param_group":"rectifier"},{"key":"Ia_peak","display_name":"Peak Anode Current (surge)","value":"1000","numeric_value":"1000","unit":"mA","param_group":"rectifier"},{"key":"Idc_max","display_name":"Max DC Output Current (total, not per-anode)","value":"150","numeric_value":"150","unit":"mA","param_group":"rectifier"},{"key":"Rs_min","display_name":"Min Series Resistance (C-input)","value":"230","numeric_value":"230","unit":"Ω","param_group":"rectifier"}]}],"synced_at":"2026-04-08T07:55:53.300Z"}