{"type_number":"6AX4","canonical_url":"https://tubeofile.com/tubes/6AX4","manufacturer":"Tung-Sol","tube_type_key":"rectifier","tube_type_display_name":"Rectifier","base_name":"Octal","description":"Single indirectly-heated diode designed for use as a horizontal-frequency damper in television receivers. Features a coated unipotential cathode and is designed to withstand high voltage pulses between cathode, heater, and plate elements in direct-drive circuits.","is_directly_heated":false,"completeness":"high","notes":["Damper diode only — power rectifier operation is not recommended per the Tung-Sol datasheet. Do not use as a conventional power supply rectifier.","Pin 2 is an internal connection and must not be used as a tie point. Pins 1, 2, 4, and 6 shall not be used as tie points.","Pin 1 is omitted on bases BS-82, BS-85, and BS-147.","Base is JEDEC 4CG (5-pin Octal). Available in Intermediate Shell (BS-82, BS-85, BS-147) and Short Intermediate Shell (B6-60) variants.","Maximum heater-cathode voltage ratings are asymmetric: heater negative 900V DC / 4400V peak, heater positive 100V DC / 300V peak. The 4400V peak rating is critical in TV damper service where the cathode sees flyback pulses.","6AX4GTA and 6AX4GTB are improved versions with different ratings — TDSL lists them as 'different rating or performance' substitutes.","Brans Vademecum groups the 6AX4GT family with EY81, PY81, PY800, 6W4GT, 6U4GT, and many heater-voltage variants (12AX4GT, 17AX4GT, 25AX4GT).","Radiomuseum confirms: Damper diode, 4.4 kV max PIV, 137 mA max DC, 825 mA peak."],"references":["https://frank.pocnet.net/sheets/127/6/6AX4GT.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=6AX4GT","radiomuseum":"https://www.radiomuseum.org/tubes/tube_6ax4gt.html"},"raw_equivalents":["6AX4GT","6AX4GTA","6AX4GTB"],"equivalents":[],"similar":[{"type_number":"6AX3","reason":"Same damper diode family (Brans groups together) but different base and ratings","has_detail_page":false},{"type_number":"6W4GT","reason":"Same function (half-wave damper diode, 6.3V heater, Octal) with similar ratings but lower PIV (1450V vs 4400V) — verify circuit boost voltage before substituting","has_detail_page":false}],"pins":[{"pin_number":"2","function":"Internal Connection — Do Not Use","function_code":"ia","notes":null},{"pin_number":"3","function":"Cathode","function_code":"k","notes":null},{"pin_number":"5","function":"Plate (Anode)","function_code":"a","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":"1.2","numeric_value":"1.2","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Damper Diode","tube_type_key":"rectifier","specs":[{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"5.0","numeric_value":"5","unit":"W","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"4400","numeric_value":"4400","unit":"V","param_group":"absolute_max"},{"key":"PIV","display_name":"Peak Inverse Voltage","value":"4400","numeric_value":"4400","unit":"V","param_group":"rectifier"},{"key":"Vdrop","display_name":"Voltage Drop (typical)","value":"32","numeric_value":"32","unit":"V","param_group":"rectifier"},{"key":"Idc_max","display_name":"Max DC Output Current (total, not per-anode)","value":"137","numeric_value":"137","unit":"mA","param_group":"rectifier"},{"key":"Ia_peak","display_name":"Peak Anode Current (surge)","value":"825","numeric_value":"825","unit":"mA","param_group":"rectifier"}]}],"synced_at":"2026-04-08T07:51:39.277Z"}