{"type_number":"EL61","canonical_url":"https://tubeofile.com/tubes/EL61","manufacturer":"Philips","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"Loctal","description":"Output pentode with 18 W anode dissipation; indirectly heated. Philips design on the rare Loctal 9-pin (B9G) base, appearing briefly from approximately 1947-1950. Superseded almost immediately by the EL34 on the Octal base. Extremely rare — practically never found its way into commercial audio amplifiers.","is_directly_heated":false,"completeness":"medium","notes":["The EL61 appeared on the market for only a brief period (approx. 1947-1950) before being superseded by the EL34.","Uses the Loctal 9-pin (B9G) base which was practically not used for the private/consumer market, contributing to its extreme rarity.","Described as 'a weaker (18 instead of 25 W) output tube' compared to the EL34 that replaced it.","Heater current of 1.35 A — same as the EL5/EL35 family.","Historical curiosity rather than a practically useful type. Very few specimens survive."],"references":["https://tdsl.duncanamps.com/show.php?des=EL61","https://www.radiomuseum.org/tubes/?tube=EL61"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=EL61","radiomuseum":"https://www.radiomuseum.org/tubes/tube_el61.html"},"raw_equivalents":[],"equivalents":[],"similar":[{"type_number":"4689","reason":"Related type listed as similar by Radiomuseum","has_detail_page":true},{"type_number":"EL34","reason":"Octal successor that replaced the EL61 almost immediately — 25 W Pa_max, universally adopted","has_detail_page":true},{"type_number":"EL5","reason":"Same 18 W power class but P8A side-contact base — electrically similar","has_detail_page":true},{"type_number":"EL5/375","reason":"Higher-voltage variant of the EL5 family, listed as similar","has_detail_page":false}],"pins":[{"pin_number":"1","function":"Suppressor Grid (g3)","function_code":"g3","notes":null},{"pin_number":"2","function":"Heater","function_code":"h","notes":null},{"pin_number":"3","function":"Anode","function_code":"a","notes":null},{"pin_number":"4","function":"Screen Grid (g2)","function_code":"g2","notes":null},{"pin_number":"5","function":"Control Grid (g1)","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":"9","function":"Metallization / Shield","function_code":"ia","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":"1.35","numeric_value":"1.35","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Pentode","tube_type_key":"power_pentode","specs":[{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"18","numeric_value":"18","unit":"W","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":"mAa","display_name":"Anode Current","value":"45","numeric_value":"45","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"100000","numeric_value":"100000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"8.0","numeric_value":"8","unit":"mA/V","param_group":"typical_operating"}]}],"synced_at":"2026-04-07T12:46:25.278Z"}