{"type_number":"EL8","canonical_url":"https://tubeofile.com/tubes/EL8","manufacturer":"Valvo","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"P8A","description":"Audio frequency beam power tube with P8A side-contact base. Electrically identical to the EL13 (Y8A steel base) and the AC-heater equivalent of the UL2 (35 V series heater). Designed for small domestic receiver output stages, delivering approximately 5 W anode dissipation at 250 V. Introduced by Valvo in 1949 as part of the Philips 'gold' transitional series before Rimlock types became available. Succeeded by the EL42 (Rimlock).","is_directly_heated":false,"completeness":"medium","notes":["The EL8 is the P8A side-contact version of the EL13 (Y8A steel base). Both share identical electrical characteristics but different bases, so they are not interchangeable without an adapter.","The suppressor 'grid' consists of only two rods and the plate is elliptical — a minimal suppressor structure typical of beam power designs.","Part of the Philips/Valvo transitional 'gold' series that bridged the pre-war side-contact range and the post-war Rimlock types. Other tubes in this series included EBF2, EBL1, ECH4, EF6, EF9, and EM4.","Pin functions could not be confirmed from any available datasheet for the EL8 specifically. The pinout listed is inferred from the EL13 (Y8A) pinout documented by r-type.org, but the P8A base has different pin geometry so exact pin numbering may differ. Use with caution — verify against the physical tube or original documentation before wiring.","Several maximum ratings (Va_max, Vs_max, Pa_max, Ps_max, Ik_max, Vhk_max, Rg_max) could not be confirmed from available sources. The EL8 is a rare and poorly documented type with no online datasheets found."],"references":["https://www.radiomuseum.org/tubes/tube_el8.html","https://www.r-type.org/exhib/aai0177.htm"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=EL8","radiomuseum":"https://www.radiomuseum.org/tubes/tube_el8.html"},"raw_equivalents":["TEL8"],"equivalents":[],"similar":[{"type_number":"EL13","reason":"Electrically identical but uses Y8A steel base — not P8A side-contact","has_detail_page":true},{"type_number":"EL42","reason":"Successor type on Rimlock base — different base, not pin-compatible","has_detail_page":true},{"type_number":"UL2","reason":"Electrically similar but 35 V series heater instead of 6.3 V — different heater and same P8A base but not a drop-in due to heater difference","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Screen Grid (inferred from EL13 Y8A pinout — verify before use)","function_code":"g2","notes":null},{"pin_number":"2","function":"Control Grid (inferred from EL13 Y8A pinout — verify before use)","function_code":"g1","notes":null},{"pin_number":"3","function":"Cathode + Suppressor Grid (inferred from EL13 Y8A pinout — verify before use)","function_code":"k","notes":null},{"pin_number":"4","function":"No Connection (inferred from EL13 Y8A pinout — verify before use)","function_code":"nc","notes":null},{"pin_number":"5","function":"Heater (inferred from EL13 Y8A pinout — verify before use)","function_code":"h","notes":null},{"pin_number":"6","function":"Heater (inferred from EL13 Y8A pinout — verify before use)","function_code":"h","notes":null},{"pin_number":"7","function":"No Connection (inferred from EL13 Y8A pinout — verify before use)","function_code":"nc","notes":null},{"pin_number":"8","function":"Anode (inferred from EL13 Y8A pinout — verify before use)","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":"0.5","numeric_value":"0.5","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Pentode","tube_type_key":"power_pentode","specs":[{"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":"-7.5","numeric_value":"-7.5","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"20","numeric_value":"20","unit":"mA","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"5.5","numeric_value":"5.5","unit":"mA/V","param_group":"typical_operating"}]}],"synced_at":"2026-04-07T12:46:30.069Z"}