{"type_number":"ECC35","canonical_url":"https://tubeofile.com/tubes/ECC35","manufacturer":"Mullard","tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Octal","description":"High-gain double triode with separate cathodes for use in paraphase A.F. voltage amplifiers.","is_directly_heated":false,"completeness":"high","notes":["Heater current is 0.4 A — higher than the 6SL7GT (0.3 A). Not a drop-in replacement in heater-current-limited designs.","Mullard ECC35 has mu of 68 and ra of 34 kΩ at Va=250V, Vg=-2.5V. The American 6SL7GT is rated mu=70, ra=44 kΩ at Va=250V, Vg=-2V. Electrically similar but not identical.","Va(b) max of 550 V is the maximum anode voltage at zero anode current (no-signal or blocked condition), not the operating maximum."],"references":["https://frank.pocnet.net/sheets/129/e/ECC35.pdf","https://frank.pocnet.net/sheets/154/e/ECC35.pdf"],"source_urls":{"r_type":"http://www.r-type.org/exhib/aau0003.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=ECC35","radiomuseum":"https://www.radiomuseum.org/tubes/tube_ecc35.html"},"raw_equivalents":["CV569","VT-229","CV1426","6SL7"],"equivalents":[{"type_number":"6SL7","equivalence_type":"direct","notes":null}],"similar":[{"type_number":"6N9S","reason":"Russian equivalent of 6SL7GT. Same Octal pinout but same electrical differences as 6SL7GT vs ECC35 (heater current 0.3A vs 0.4A, mu 70 vs 68).","has_detail_page":false},{"type_number":"6SL7GT","reason":"Electrically similar but different heater current (0.3A vs 0.4A), mu (70 vs 68), and ra (44k vs 34k ohms) — not a drop-in in heater-current-limited designs","has_detail_page":false}],"pins":[{"pin_number":"1","function":"Control Grid (section 2)","function_code":"g1_2","notes":null},{"pin_number":"2","function":"Anode (section 2)","function_code":"a2","notes":null},{"pin_number":"3","function":"Cathode (section 2)","function_code":"k2","notes":null},{"pin_number":"4","function":"Control Grid (section 1)","function_code":"g1_1","notes":null},{"pin_number":"5","function":"Anode (section 1)","function_code":"a1","notes":null},{"pin_number":"6","function":"Cathode (section 1)","function_code":"k1","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":"0.4","numeric_value":"0.4","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode (each section)","tube_type_key":"small_signal_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"1.5","numeric_value":"1.5","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"8","numeric_value":"8","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"90","numeric_value":"90","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"1.5","numeric_value":"1.5","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"250","numeric_value":"250","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-2.5","numeric_value":"-2.5","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"2.3","numeric_value":"2.3","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"34000","numeric_value":"34000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"2.0","numeric_value":"2","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"68","numeric_value":"68","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"2.5","numeric_value":"2.5","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"3.0","numeric_value":"3","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"1.0","numeric_value":"1","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"Inter-anode Capacitance (Ca'-a\")","value":"0.75","numeric_value":"0.75","unit":"pF","param_group":null}]}],"synced_at":"2026-04-07T19:07:11.378Z"}