{"type_number":"EL38","canonical_url":"https://tubeofile.com/tubes/EL38","manufacturer":"Mullard","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"Octal","description":"Output pentode primarily intended for use as line time base output valve in A.C. television receivers.","is_directly_heated":false,"completeness":"high","notes":["Anode connection is via top cap, not through the octal base.","Originally designed for TV line output (horizontal deflection) service, not audio. The anode can withstand peak pulses up to 8 kV in deflection circuits.","For audio service, do not exceed approximately 22 W static anode dissipation despite the 25 W maximum rating — localised hot spots on the anode have been reported at higher sustained dissipation.","Max grid resistor depends on anode dissipation: 500 kOhm when Pa < 25 W, 800 kOhm when Pa < 9 W.","PL38 is a near equivalent with a different heater voltage (300 mA series heater). EL38M is a slightly different variant.","Philips datasheet provides a second operating point at Va = 600 V, Vg2 = 400 V: Ia = 42 mA, Ig2 = 5 mA, Vg1 = -22 V, gm = 7.0 mA/V, ra = 43 kOhm.","Triode-strapped data (mu, gm, ra) sourced from Tom Schlangen's 'Pentodes Strapped as Triodes' table (2009) and estimated operating point from Patrick Turner via rec.audio.tubes (https://rec.audio.tubes.narkive.com/12sQdJgo/el38-6cn6-triode-strapped-data), not from the manufacturer datasheet.","No audio output power or load impedance is specified in the manufacturer datasheets for pentode mode — the tube was rated only for deflection service."],"references":["https://frank.pocnet.net/sheets/129/e/EL38.pdf","https://frank.pocnet.net/sheets/030/e/EL38.pdf","http://www.r-type.org/exhib/aam0020.htm","https://rec.audio.tubes.narkive.com/12sQdJgo/el38-6cn6-triode-strapped-data"],"source_urls":{"r_type":"http://www.r-type.org/exhib/aam0020.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=EL38","radiomuseum":"https://www.radiomuseum.org/tubes/tube_el38.html"},"raw_equivalents":["6CN6","CV450","CV8038","5P29","EL38M"],"equivalents":[],"similar":[{"type_number":"PL38","reason":"Series-heater equivalent (300mA) — not compatible with 6.3V parallel heater circuits","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Suppressor Grid","function_code":"g3","notes":null},{"pin_number":"2","function":"Heater","function_code":"h","notes":null},{"pin_number":"3","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"4","function":"Screen Grid","function_code":"g2","notes":null},{"pin_number":"5","function":"Control Grid","function_code":"g1","notes":null},{"pin_number":"6","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","notes":null},{"pin_number":"8","function":"Cathode","function_code":"k","notes":null},{"pin_number":"TC","function":"Anode (Top Cap)","function_code":"a","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":"1.4","numeric_value":"1.4","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Pentode","tube_type_key":"power_pentode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"800","numeric_value":"800","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"400","numeric_value":"400","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"25","numeric_value":"25","unit":"W","param_group":"absolute_max"},{"key":"Ps_max","display_name":"Screen Dissipation (max)","value":"8","numeric_value":"8","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"200","numeric_value":"200","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":"0.5","numeric_value":"0.5","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"275","numeric_value":"275","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"275","numeric_value":"275","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-9","numeric_value":"-9","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"91","numeric_value":"91","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"11","numeric_value":"11","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"20000","numeric_value":"20000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"14","numeric_value":"14","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"16.5","numeric_value":"16.5","unit":"—","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"120","numeric_value":"120","unit":"Ω","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"1.2","numeric_value":"1.2","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"18","numeric_value":"18","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"8","numeric_value":"8","unit":"pF","param_group":"capacitances"}]},{"section_number":2,"section_label":"Triode Strapped","tube_type_key":"power_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"400","numeric_value":"400","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"25","numeric_value":"25","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"200","numeric_value":"200","unit":"mA","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"300","numeric_value":"300","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"60","numeric_value":"60","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"1000","numeric_value":"1000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"12","numeric_value":"12","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"12","numeric_value":"12","unit":"—","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"3.6","numeric_value":"3.6","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"3100","numeric_value":"3100","unit":"Ω","param_group":"output"}]}],"synced_at":"2026-04-07T19:08:40.064Z"}