{"type_number":"6325","canonical_url":"https://tubeofile.com/tubes/6325","manufacturer":"Philco","tube_type_key":"rectifier","tube_type_display_name":"Rectifier","base_name":"Octal","description":"Full-wave high-vacuum rectifier intended for high-voltage industrial power supplies. Indirectly heated twin diode with a 780 V RMS per-plate rating and 250 mA total DC output, housed in a T-9 glass envelope on a short-shell low-loss octal base. Significantly higher voltage capability than typical 6.3 V rectifiers.","is_directly_heated":false,"completeness":"high","notes":["High-voltage industrial rectifier — PIV 2200 V and RMS plate-supply voltage 780 V per plate, well beyond common receiving-tube rectifiers. Peak inverse under full load at 780 V RMS supply is 975 V (per life-test data), with absolute PIV 2200 V.","Classification: full-wave high-vacuum rectifier per Philco March 30, 1953 datasheet and GE 1973 Essential Characteristics. NOT a mercury-vapour or thyratron type — it is a conventional indirectly heated hard-vacuum rectifier despite the unusually high voltage rating.","Heater current is high (2.7 A) to sustain the large cathode area required for the 250 mA DC output at elevated plate voltage.","Filament voltage must be applied one full minute before plate voltage to allow cathode warm-up — applying plate voltage to a cold cathode will cause emission damage.","Ruggedised: tubes withstand 450 g impact shock at 30° hammer angle (Taft-Pierce shock tester).","Common-cathode topology (single cathode on pin 1) — conventional full-wave rectifier connection, not suitable for voltage doubling.","Life-test data: 550 hr life expectancy ≥ 90%, 1000 hr ≥ 80%, at ambient 125 °C.","Vdrop not stated explicitly in the datasheet. Datasheet Condenser-Input life-test point: Vac=350 V RMS/plate, Idc=125 mA per plate, Vdc=285 V. Ideal full-wave peak ≈ 1.41 × 350 = 494 V. Dataseet Choke-Input life-test point: Vac=780 V RMS/plate, Idc=75 mA, Vdc=650 V, Lfilt=4.5 H. Ideal DC with choke input = 0.9 × 780 = 702 V; measured 650 V → total drop ≈ 52 V including series resistance. Rs per plate 250 Ω × 0.075 A ≈ 19 V, leaving tube drop ≈ 33 V at 75 mA per plate. Recorded as approximate value derived from regulation table."],"references":["https://frank.pocnet.net/sheets/201/6/6325.pdf","https://www.radiomuseum.org/tubes/tube_6325.html"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=6325","radiomuseum":"https://www.radiomuseum.org/tubes/tube_6325.html"},"raw_equivalents":[],"equivalents":[],"similar":[{"type_number":"5R4GY","reason":"Octal full-wave rectifier with comparable voltage class, but directly heated 5 V filament and different pinout — not pin-compatible","has_detail_page":false},{"type_number":"5U4G","reason":"Octal high-voltage full-wave rectifier, but directly heated 5 V filament and different pinout — not pin-compatible","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Cathode (common)","function_code":"k","notes":null},{"pin_number":"2","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"3","function":"Plate 1 (Anode 1)","function_code":"a1","notes":null},{"pin_number":"4","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"5","function":"Plate 2 (Anode 2)","function_code":"a2","notes":null},{"pin_number":"6","function":"Internal Connection","function_code":"ic","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","notes":null},{"pin_number":"8","function":"Heater","function_code":"h","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":"2.7","numeric_value":"2.7","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":"780","numeric_value":"780","unit":"V","param_group":"absolute_max"},{"key":"PIV","display_name":"Peak Inverse Voltage","value":"2200","numeric_value":"2200","unit":"V","param_group":"rectifier"},{"key":"Vdrop","display_name":"Voltage Drop (typical)","value":"33","numeric_value":"33","unit":"V","param_group":"rectifier"},{"key":"Ia_peak","display_name":"Peak Anode Current (surge)","value":"550","numeric_value":"550","unit":"mA","param_group":"rectifier"},{"key":"Idc_max","display_name":"Max DC Output Current (total, not per-anode)","value":"250","numeric_value":"250","unit":"mA","param_group":"rectifier"}]}],"synced_at":"2026-04-09T05:16:53.063Z"}