{"type_number":"EL35","canonical_url":"https://tubeofile.com/tubes/EL35","manufacturer":"Mullard","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"Octal","description":"Output pentode with 18 W anode dissipation; indirectly heated. Mullard/Philips type with International Octal (IO/K8A) base — the Octal-based equivalent of the EL5 (P8A side-contact base). Introduced for equipment using the standardized Octal socket system.","is_directly_heated":false,"completeness":"medium","notes":["The EL35 is the Octal-base version of the EL5. Electrically identical but uses the International Octal (IO) base instead of the P8A side-contact base.","Brans Vademecum lists EL35 with equivalents including EL5, EL50, EL12/325, EL12/375, EL12spez, 4654K, and 4689P — all in the same power pentode family.","CV1286 is the UK military designation.","Very rare tube — found in only 3 radio models at Radiomuseum (dated 1945 and 1950).","Heater current 1.35 A — not suitable for series-heater strings.","Anode connection via top cap for improved high-voltage isolation."],"references":["https://tdsl.duncanamps.com/show.php?des=EL35","https://www.radiomuseum.org/tubes/?tube=EL35"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=EL35","radiomuseum":"https://www.radiomuseum.org/tubes/tube_el35.html"},"raw_equivalents":["CV1286"],"equivalents":[],"similar":[{"type_number":"EL12","reason":"Related power pentode in the same Brans family — Y8A base, different pinout","has_detail_page":true},{"type_number":"EL12spez","reason":"Higher-voltage variant in the same family — Y8A base, different pinout","has_detail_page":true},{"type_number":"EL5","reason":"Electrically identical but P8A side-contact base — not pin-compatible with Octal sockets","has_detail_page":true},{"type_number":"EL50","reason":"Listed in Brans as equivalent — similar power pentode","has_detail_page":true}],"pins":[{"pin_number":"1","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"2","function":"Heater","function_code":"h","notes":null},{"pin_number":"3","function":"Screen Grid (g2)","function_code":"g2","notes":null},{"pin_number":"4","function":"Control Grid (g1)","function_code":"g1","notes":null},{"pin_number":"5","function":"Suppressor Grid (g3)","function_code":"g3","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":"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":"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":"Vg","display_name":"Grid 1 Bias Voltage","value":"-16","numeric_value":"-16","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"72","numeric_value":"72","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"7.5","numeric_value":"7.5","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"33000","numeric_value":"33000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"7","numeric_value":"7","unit":"mA/V","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"200","numeric_value":"200","unit":"Ω","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"7.7","numeric_value":"7.7","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"3500","numeric_value":"3500","unit":"Ω","param_group":"output"}]}],"synced_at":"2026-04-07T12:44:16.321Z"}