{"type_number":"B36","canonical_url":"https://tubeofile.com/tubes/B36","manufacturer":"Marconi-Osram (GEC)","tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Octal","description":"Medium-mu double triode, indirectly heated, with 12.6V heater. British (Marconi-Osram / GEC) equivalent of the American 12SN7GT. Identical to the B65 apart from heater ratings (B65 uses 6.3V heater).","is_directly_heated":false,"completeness":"high","notes":["The B36 and B65 are identical apart from their heater ratings (B36: 12.6V/0.3A, B65: 6.3V/0.6A). The datasheet covers both types.","Grid-cathode DC resistance must not exceed 1 MΩ per section under maximum rated conditions.","First introduced in 1948 by Marconi-Osram Valve Company (M-OV), a division of GEC. Some early production examples have metal bases, which are now highly sought after by collectors.","Howard W. Sams Tube Substitution Handbook (1973) and Philips Interchange Guide (1962) both confirm B36 = 12SN7GT.","The Marconi B36/B65 has lower maximum ratings than the standard 6SN7/12SN7 (Pa_max 2.5W vs 5W, Va_max 300V vs 450V). A 12SN7GT can always replace a B36, but a B36 may not be safe in circuits that operate near the higher American ratings."],"references":["https://frank.pocnet.net/sheets/126/b/B36.pdf","http://www.r-type.org/exhib/aaa0516.htm"],"source_urls":{"r_type":"http://www.r-type.org/exhib/aaa0516.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=B36","radiomuseum":"https://www.radiomuseum.org/tubes/tube_b36.html"},"raw_equivalents":["12SN7GT","12SN7GTA","12SN7","CV925","B65","6SN7GT","6SN7GTA","6SN7GTB","6SN7W","VT-231","CV181","6N8S","6H8C","6SN7"],"equivalents":[{"type_number":"6SN7","equivalence_type":"direct","notes":null}],"similar":[],"pins":[{"pin_number":"1","function":"Control Grid (section 2)","function_code":"g1_2","notes":null},{"pin_number":"2","function":"Anode (section 2)","function_code":"a2","notes":null},{"pin_number":"3","function":"Cathode (section 2)","function_code":"k2","notes":null},{"pin_number":"4","function":"Control Grid (section 1)","function_code":"g1_1","notes":null},{"pin_number":"5","function":"Anode (section 1)","function_code":"a1","notes":null},{"pin_number":"6","function":"Cathode (section 1)","function_code":"k1","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":"12.6","numeric_value":"12.6","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.3","numeric_value":"0.3","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode (each section)","tube_type_key":"small_signal_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"2.5","numeric_value":"2.5","unit":"W","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"150","numeric_value":"150","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"1","numeric_value":"1","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"250","numeric_value":"250","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-8","numeric_value":"-8","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"9","numeric_value":"9","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"7700","numeric_value":"7700","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"2.6","numeric_value":"2.6","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"20","numeric_value":"20","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"4.5","numeric_value":"4.5","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"3.5","numeric_value":"3.5","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"1.5","numeric_value":"1.5","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"Vg for cut-off (Ia = 10 µA)","value":"-17","numeric_value":"-17","unit":"V","param_group":null}]}],"synced_at":"2026-04-07T19:06:07.833Z"}