{"type_number":"EL41","canonical_url":"https://tubeofile.com/tubes/EL41","manufacturer":"Philips","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"Rimlock","description":"Output pentode intended for use in AC mains operated equipment with self-bias or semi-automatic bias. Rimlock B8A predecessor to the EL84.","is_directly_heated":false,"completeness":"high","notes":["Screen dissipation has two separate limits: max 1.4 W at zero signal (idle) and max 3.3 W at maximum output power. The idle operating point must be designed so that Ps ≤ 1.4 W; higher dissipation is only permissible under signal drive.","Vhk_max was 50 V in the 1949 Miniwatt datasheet and raised to 100 V in the 1952 Philips datasheet. The 100 V figure is used here.","The EL41 (Rimlock B8A base) is electrically similar to the EL84 (Noval 9-pin) but pin-incompatible. A base adapter is required for substitution.","Output power is tabulated as 3.9 W at 10% THD in the official Philips datasheet. Brimar and TDSL cite 4.2 W for the same conditions, likely from the peak optimum load point on the output curves rather than the tabulated operating point.","Class AB push-pull (2× EL41): Va = 250 V, Vg2 = 250 V, Rk = 85 Ω, Raa = 7 kΩ (plate-to-plate). Delivers 9.4 W at 4.6% THD.","Pins 3 and 4 are cathode/suppressor internal connections and may be left unconnected at the socket. Pin 7 is the main external cathode connection. All three are electrically the cathode.","In triode connection: strap g2 (pin 5) directly to anode (pin 2). Ra = 3.5 kΩ in the datasheet is the recommended anode load impedance; internal plate resistance in triode mode is not tabulated."],"references":["https://tube-data.com/sheets/030/e/EL41.pdf","https://tube-data.com/sheets/155/e/EL41.pdf"],"source_urls":{"r_type":"http://www.r-type.org/exhib/aaa0363.htm","tdsl":"http://tdsl.duncanamps.com/show.php?des=EL41","radiomuseum":null},"raw_equivalents":["CV3889","6CK5","67PT","N150","N41"],"equivalents":[],"similar":[{"type_number":"EL84","reason":"Electrically similar successor but Noval base vs Rimlock — not pin-compatible, requires adapter","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Heater","function_code":"h","notes":null},{"pin_number":"2","function":"Anode","function_code":"a","notes":null},{"pin_number":"3","function":"Cathode (internal connection)","function_code":"k","notes":null},{"pin_number":"4","function":"Cathode / Suppressor Grid (internal; g3 tied to cathode)","function_code":"g3","notes":null},{"pin_number":"5","function":"Screen Grid","function_code":"g2","notes":null},{"pin_number":"6","function":"Control Grid","function_code":"g1","notes":null},{"pin_number":"7","function":"Cathode","function_code":"k","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":"0.71","numeric_value":"0.71","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":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"9","numeric_value":"9","unit":"W","param_group":"absolute_max"},{"key":"Ps_max","display_name":"Screen Dissipation (max)","value":"3.3","numeric_value":"3.3","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"55","numeric_value":"55","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":"1","numeric_value":"1","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":"Vs","display_name":"Screen Voltage (typical)","value":"250","numeric_value":"250","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-7.0","numeric_value":"-7","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"36","numeric_value":"36","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"5.2","numeric_value":"5.2","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"40000","numeric_value":"40000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"10","numeric_value":"10","unit":"mA/V","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"170","numeric_value":"170","unit":"Ω","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"3.9","numeric_value":"3.9","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"7000","numeric_value":"7000","unit":"Ω","param_group":"output"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"<1","numeric_value":null,"unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"10.2","numeric_value":"10.2","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"7.8","numeric_value":"7.8","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"μg2g1","value":"22","numeric_value":"22","unit":"—","param_group":null},{"key":null,"display_name":"Rfk","value":"20000","numeric_value":"20000","unit":"Ω","param_group":null}]},{"section_number":2,"section_label":"Triode Strapped","tube_type_key":"power_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":"9","numeric_value":"9","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"55","numeric_value":"55","unit":"mA","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"1","numeric_value":"1","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":"-8.25","numeric_value":"-8.25","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"33","numeric_value":"33","unit":"mA","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"250","numeric_value":"250","unit":"Ω","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"1.55","numeric_value":"1.55","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"3500","numeric_value":"3500","unit":"Ω","param_group":"output"}]}],"synced_at":"2026-04-07T12:45:05.326Z"}