{"type_number":"UL2","canonical_url":"https://tubeofile.com/tubes/UL2","manufacturer":"Valvo","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"P8A","description":"Audio frequency beam power pentode with P8A side-contact base. 100 mA series-heater version of the EL8. Designed for small domestic receiver output stages in AC/DC series-string sets, delivering approximately 5 W anode dissipation at 250 V.","is_directly_heated":false,"completeness":"medium","notes":["Series-heater (100 mA) version of the EL8/EL2. Electrically identical sections — only the heater voltage/current differs (35 V at 100 mA vs 6.3 V at 500 mA).","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 series for AC/DC receivers with series-string heaters.","Pin functions inferred from EL8/EL13 pinout — verify against original documentation before wiring.","A rare and poorly documented type. Maximum ratings carried over from EL8 data where available."],"references":["https://www.radiomuseum.org/tubes/tube_ul2.html"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=UL2","radiomuseum":"https://www.radiomuseum.org/tubes/tube_ul2.html"},"raw_equivalents":[],"equivalents":[],"similar":[{"type_number":"EL13","reason":"Electrically identical to EL8 but uses Y8A steel base — different base from both EL8 and UL2","has_detail_page":true},{"type_number":"EL42","reason":"Successor type on Rimlock base — different base, not pin-compatible","has_detail_page":true},{"type_number":"EL8","reason":"Identical electricals but 6.3 V parallel heater — not a drop-in in series-string heater circuits","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":"35","numeric_value":"35","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.1","numeric_value":"0.1","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":"2026-04-07T12:52:31.249Z"}