{"type_number":"KT170","canonical_url":"https://tubeofile.com/tubes/KT170","manufacturer":"Tung-Sol","tube_type_key":"beam_tetrode","tube_type_display_name":"Beam Tetrode","base_name":"Octal","description":"Beam tetrode in original shape glass bulb with octal base and equipotential cathode, designed to amplify low frequency power in the output stages of Hi-Fi audio. 85 W anode dissipation — the largest and most powerful tube in the 6550/KT88/KT90/KT120/KT150 series. A pair in Class AB push-pull can deliver in excess of 300 W.","is_directly_heated":false,"completeness":"medium","notes":["The Tung-Sol datasheet is notably incomplete: no explicit Va_max or Vs_max ratings are specified. The operating conditions limits section lists Pa_max, Ps_max, Ik_max, Vhk_max, and Rg_max but omits maximum plate and screen voltages. The plate characteristic curves extend to 500 V.","The datasheet specifies only a single SE operating point (Va=400 V, Vg2=225 V). No push-pull operating conditions are provided despite the 300 W PP claim.","Pin 1 is the outer metal screen (electrostatic shield). Pin 6 is empty (no physical pin). Pin 8 is cathode with beam-forming screen connected internally.","Heater current is specified as a range of 1.75–2.0 A. Radiomuseum.org lists a typical value of 1.85 A.","First grid cut-off voltage is −60 V (at Va=400 V, Vg2=225 V).","No triode-strapped operating data is published by the manufacturer. A diyAudio user (KoitoYuu) traced triode curves but did not publish mu, gm, or ra values. The user measured interelectrode capacitances in triode mode: Ck-g1=25 pF, Cg1-g2=18 pF, Ck-g2=20 pF."],"references":["https://shop.ehx.com/catalog/tubes-specs/KT170%20TS.pdf","https://frank.pocnet.net/sheets/084/k/KT%20170_TungSol.pdf"],"source_urls":{"r_type":null,"tdsl":null,"radiomuseum":"https://www.radiomuseum.org/tubes/tube_kt170.html"},"raw_equivalents":[],"equivalents":[],"similar":[{"type_number":"KT120","reason":"Same Tung-Sol octal beam tetrode family. KT170 has much higher Pa_max (85W vs 60W). Same pin functions but different operating points and heater current.","has_detail_page":true},{"type_number":"KT150","reason":"Same Tung-Sol octal beam tetrode family. KT170 has higher Pa_max (85W vs 70W). Same pin functions but different operating points.","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Outer Metal Screen","function_code":"ia","notes":null},{"pin_number":"2","function":"Heater","function_code":"h","notes":null},{"pin_number":"3","function":"Plate (Anode)","function_code":"a","notes":null},{"pin_number":"4","function":"Grid 2 (Screen Grid)","function_code":"g2","notes":null},{"pin_number":"5","function":"Grid 1 (Control Grid)","function_code":"g1","notes":null},{"pin_number":"6","function":"Empty (No Connection)","function_code":"nc","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","notes":null},{"pin_number":"8","function":"Cathode, Beam-Forming Screen","function_code":"k","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":"1.85","numeric_value":"1.85","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Beam Tetrode","tube_type_key":"beam_tetrode","specs":[{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"85","numeric_value":"85","unit":"W","param_group":"absolute_max"},{"key":"Ps_max","display_name":"Screen Dissipation (max)","value":"11","numeric_value":"11","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"300","numeric_value":"300","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"0.51","numeric_value":"0.51","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"400","numeric_value":"400","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"225","numeric_value":"225","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-14","numeric_value":"-14","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"155","numeric_value":"155","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"25","numeric_value":"25","unit":"mA","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"14","numeric_value":"14","unit":"mA/V","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"24","numeric_value":"24","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"3000","numeric_value":"3000","unit":"Ω","param_group":"output"},{"key":null,"display_name":"First Grid Reverse Current (max)","value":"1.2","numeric_value":"1.2","unit":"µA","param_group":null},{"key":null,"display_name":"First Grid Alternating Voltage (efficacious)","value":"9.9","numeric_value":"9.9","unit":"V","param_group":null},{"key":null,"display_name":"First Grid Cut-off Voltage","value":"-60","numeric_value":"-60","unit":"V","param_group":null}]}],"synced_at":"2026-04-07T12:48:54.909Z"}