{"type_number":"5X4","canonical_url":"https://tubeofile.com/tubes/5X4","manufacturer":null,"tube_type_key":"rectifier","tube_type_display_name":"Rectifier","base_name":"Octal","description":"Full-wave vacuum rectifier, directly heated (filament cathode). Electrically identical to 5U4G and 5Z3 but with a unique octal pinout — plates on pins 3 and 5, filaments on pins 7 and 8. Designed for use with center-tapped transformer in full-wave configuration, delivering up to 225 mA DC output. Only manufactured in ST glass envelope (hence also designated 5X4G).","is_directly_heated":true,"completeness":"high","notes":["Directly heated (filament cathode) — observe heater warm-up time before applying B+ to protect the tube and filter capacitors.","Electrically identical to 5U4G and 5Z3 but NOT pin-compatible. The 5X4 has plates on pins 3 and 5, filaments on pins 7 and 8; the 5U4G has plates on pins 4 and 6, filaments on pins 2 and 8. The 5Z3 uses a 4-pin UX4 base. Socket wiring must be changed to substitute between these types.","Only produced in ST (shoulder) glass envelope — all specimens are effectively 5X4G. There is no metal or GT variant.","Primarily used by Zenith; RCA radios of the same era used the pin-compatible 5U4G instead.","Relatively high voltage drop (~58 V at 225 mA) compared to indirectly-heated rectifiers like 5AR4/GZ34 (~15 V). This provides natural 'soft start' characteristics valued in audio equipment."],"references":["https://frank.pocnet.net/sheets/127/5/5X4G.pdf","http://vinylsavor.blogspot.com/2013/07/tube-of-month-5x4.html"],"source_urls":{"r_type":null,"tdsl":"http://tdsl.duncanamps.com/show.php?des=5X4G","radiomuseum":"https://www.radiomuseum.org/tubes/tube_5x4.html"},"raw_equivalents":["5X4G","5X4GA","CV1852"],"equivalents":[],"similar":[{"type_number":"5U4G","reason":"Electrically identical but different Octal pinout — plates on pins 4/6 vs 3/5","has_detail_page":true},{"type_number":"5Z3","reason":"Electrically identical but uses UX4 (4-pin) base","has_detail_page":true}],"pins":[{"pin_number":"1","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"2","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"3","function":"Anode 1 (Plate 1)","function_code":"a1","notes":null},{"pin_number":"4","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"5","function":"Anode 2 (Plate 2)","function_code":"a2","notes":null},{"pin_number":"6","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"7","function":"Filament","function_code":"h","notes":null},{"pin_number":"8","function":"Filament","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"5.0","numeric_value":"5","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"3.0","numeric_value":"3","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":"450","numeric_value":"450","unit":"V","param_group":"absolute_max"},{"key":"PIV","display_name":"Peak Inverse Voltage","value":"1550","numeric_value":"1550","unit":"V","param_group":"rectifier"},{"key":"Vdrop","display_name":"Voltage Drop (typical)","value":"58","numeric_value":"58","unit":"V","param_group":"rectifier"},{"key":"C_max","display_name":"Max C-input Filter Capacitor","value":"40","numeric_value":"40","unit":"µF","param_group":"rectifier"},{"key":"Ia_peak","display_name":"Peak Anode Current (surge)","value":"800","numeric_value":"800","unit":"mA","param_group":"rectifier"},{"key":"Idc_max","display_name":"Max DC Output Current (total, not per-anode)","value":"225","numeric_value":"225","unit":"mA","param_group":"rectifier"}]}],"synced_at":"2026-04-08T07:50:57.562Z"}