{"type_number":"UL41","canonical_url":"https://tubeofile.com/tubes/UL41","manufacturer":"Philips","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"Rimlock","description":"Indirectly heated power output pentode designed by Philips for AC/DC series-heater radio receivers. Uses a 45V/100mA heater for series string operation. Rimlock B8A base. Introduced in 1947, succeeded by UL84 in 1955.","is_directly_heated":false,"completeness":"medium","notes":["45V/100mA heater for series string operation in AC/DC (transformerless) receivers.","Rimlock B8A base — pins 3 and 4 are internal connections.","Succeeded by UL84 in 1955."],"references":["https://frank.pocnet.net/sheets/020/u/UL41.pdf","https://frank.pocnet.net/sheets/030/u/UL41.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=UL41","radiomuseum":"https://www.radiomuseum.org/tubes/tube_ul41.html"},"raw_equivalents":["CV1977","45A5","N142"],"equivalents":[],"similar":[{"type_number":"EL41","reason":"Same pentode structure but 6.3V parallel heater — different heater circuit","has_detail_page":true},{"type_number":"UL84","reason":"Noval-based successor with improved performance — not pin-compatible","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Anode (Plate)","function_code":"a","notes":null},{"pin_number":"2","function":"Screen Grid (g2)","function_code":"g2","notes":null},{"pin_number":"3","function":"Internal Connection","function_code":"ia","notes":null},{"pin_number":"4","function":"Internal Connection","function_code":"ia","notes":null},{"pin_number":"5","function":"Cathode / Suppressor Grid (g3)","function_code":"k","notes":null},{"pin_number":"6","function":"Control Grid (g1)","function_code":"g1","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","notes":null},{"pin_number":"8","function":"Heater","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"45","numeric_value":"45","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":"200","numeric_value":"200","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"200","numeric_value":"200","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-14.2","numeric_value":"-14.2","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"45","numeric_value":"45","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"8.5","numeric_value":"8.5","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"24000","numeric_value":"24000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"8.2","numeric_value":"8.2","unit":"mA/V","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":"4.2","numeric_value":"4.2","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"4300","numeric_value":"4300","unit":"Ω","param_group":"output"}]}],"synced_at":"2026-04-07T12:52:35.702Z"}