{"type_number":"EL53","canonical_url":"https://tubeofile.com/tubes/EL53","manufacturer":"Philips","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"P8A","description":"Output pentode rated for higher voltage operation (up to 425 V); indirectly heated. Philips designation for the EL3/425 — a voltage-selected variant of the EL3 family on the P8A side-contact base. Same electrical characteristics as EL3N but rated for higher anode and screen voltages.","is_directly_heated":false,"completeness":"high","notes":["The EL53 is identical to the EL3/425 designation — a factory-selected EL3N rated for 425 V anode and screen operation.","Anode connection is via top cap. The P8A side-contact base carries heater, cathode, grids, and metallization.","Maximum voltage ratings significantly higher than the standard EL3/EL3N (250 V), enabling use in higher-power push-pull configurations.","Heater current 0.9 A (same as EL3N, using the improved profile-cathode design).","Electrical characteristics at the standard 250 V operating point are identical to the EL3N."],"references":["https://tdsl.duncanamps.com/show.php?des=EL53","https://www.radiomuseum.org/tubes/?tube=EL53"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=EL53","radiomuseum":"https://www.radiomuseum.org/tubes/tube_el53.html"},"raw_equivalents":["EL3/425"],"equivalents":[],"similar":[{"type_number":"4694","reason":"Related type listed as similar by Radiomuseum","has_detail_page":true},{"type_number":"EL3","reason":"Original design with lower voltage rating and higher heater current (1.2 A vs 0.9 A)","has_detail_page":true},{"type_number":"EL3/375","reason":"Intermediate voltage-rated variant (375 V) of the same family","has_detail_page":true},{"type_number":"EL3N","reason":"Same base and similar characteristics but lower voltage rating (250 V vs 425 V) — the EL53 is a voltage-selected EL3N","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Control Grid","function_code":"g1","notes":null},{"pin_number":"2","function":"Cathode","function_code":"k","notes":null},{"pin_number":"3","function":"Heater","function_code":"h","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Screen Grid","function_code":"g2","notes":null},{"pin_number":"6","function":"Metallization (external shield)","function_code":"ia","notes":null},{"pin_number":"7","function":"Suppressor Grid (internally connected to cathode)","function_code":"g3","notes":null},{"pin_number":"8","function":"No Connection","function_code":"nc","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":"0.9","numeric_value":"0.9","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":"425","numeric_value":"425","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"425","numeric_value":"425","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":"2.5","numeric_value":"2.5","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":"-6","numeric_value":"-6","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":"4","numeric_value":"4","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"50000","numeric_value":"50000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"9","numeric_value":"9","unit":"mA/V","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"150","numeric_value":"150","unit":"Ω","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"4.5","numeric_value":"4.5","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"7000","numeric_value":"7000","unit":"Ω","param_group":"output"}]}],"synced_at":"2026-04-07T12:45:54.947Z"}