{"type_number":"EF805S","canonical_url":"https://tubeofile.com/tubes/EF805S","manufacturer":"Telefunken","tube_type_key":"ss_pentode","tube_type_display_name":"Small Signal Pentode","base_name":"Noval","description":"Variable-mu RF/IF pentode, long-life version of EF85 with tight tolerances, shock-proof construction, and cathode free from interface","is_directly_heated":false,"completeness":"high","notes":["Long-life tube: guaranteed 10,000 hours averaged over 100 tubes, provided heater voltage is kept within ±5%","Heater current differs between manufacturers: Telefunken specifies 285 mA, AEG specifies 300 mA","Pin 1 is internally connected to pin 3 (both cathode)","Rg1 max is 3 MΩ for automatic (cathode) bias, reduced to 1.5 MΩ for fixed bias","Free socket contacts must not be used for supporting any circuitry","EF85 is the standard-life equivalent but may differ slightly in heater current and max cathode current ratings"],"references":["https://frank.pocnet.net/sheets/128/e/EF805S.pdf","https://frank.pocnet.net/sheets/173/e/EF805S.pdf"],"source_urls":{"r_type":null,"tdsl":null,"radiomuseum":"https://www.radiomuseum.org/tubes/tube_ef805s.html"},"raw_equivalents":["EF85","EF865","6BY7"],"equivalents":[],"similar":[{"type_number":"19BY7","reason":"Brans Vademecum lists as equivalent. Same B9A base and similar characteristics but 19V series-string heater — not a drop-in in 6.3V heater circuits","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Cathode (connected to pin 3)","function_code":"k","notes":null},{"pin_number":"2","function":"Control Grid","function_code":"g1","notes":null},{"pin_number":"3","function":"Cathode (connected to pin 1)","function_code":"k","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Heater","function_code":"h","notes":null},{"pin_number":"6","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"7","function":"Anode","function_code":"a","notes":null},{"pin_number":"8","function":"Screen Grid","function_code":"g2","notes":null},{"pin_number":"9","function":"Suppressor Grid","function_code":"g3","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":"0.285","numeric_value":"0.285","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Pentode","tube_type_key":"ss_pentode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"250","numeric_value":"250","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"250","numeric_value":"250","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"2","numeric_value":"2","unit":"W","param_group":"absolute_max"},{"key":"Ps_max","display_name":"Screen Dissipation (max)","value":"0.5","numeric_value":"0.5","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"16","numeric_value":"16","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"100","numeric_value":"100","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"3","numeric_value":"3","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"200","numeric_value":"200","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"200","numeric_value":"200","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-1.5","numeric_value":"-1.5","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"10","numeric_value":"10","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"2.5","numeric_value":"2.5","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"350000","numeric_value":"350000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"6.5","numeric_value":"6.5","unit":"mA/V","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"0.007","numeric_value":"0.007","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"0.1","numeric_value":"0.1","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"7.7","numeric_value":"7.7","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"3.7","numeric_value":"3.7","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"Rk","value":"120","numeric_value":"120","unit":"Ω","param_group":null},{"key":null,"display_name":"Ua0 max (no current)","value":"550","numeric_value":"550","unit":"V","param_group":null},{"key":null,"display_name":"Ug20 max (no current)","value":"550","numeric_value":"550","unit":"V","param_group":null},{"key":null,"display_name":"Rg2 min","value":"45","numeric_value":"45","unit":"kΩ","param_group":null}]}],"synced_at":"2026-04-07T19:07:48.144Z"}