{"type_number":"A2900","canonical_url":"https://tubeofile.com/tubes/A2900","manufacturer":"GEC","tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Noval","description":"Premium-grade double triode manufactured by GEC (General Electric Company, UK) and Marconi-Osram Valve Company. Electrically equivalent to ECC81/12AT7 but manufactured to tighter tolerances with closely matched sections, low noise, and low microphonics. Designed for military, instrumentation, and high-quality audio applications.","is_directly_heated":false,"completeness":"high","notes":["The A2900 is a GEC proprietary designation for a premium-grade ECC81 with tightly controlled section balance and low noise. It is functionally interchangeable with any ECC81/12AT7 circuit.","Also branded as Marconi A2900 (manufactured by MO Valve Company, England). CV6091 is the UK military designation for this high-reliability grade.","Some vendor sources claim the A2900 draws 0.4A heater current (0.1A more than standard ECC81). This is unconfirmed by manufacturer datasheets and likely refers to a specific variant or measurement anomaly. Standard ECC81 heater ratings apply."],"references":["https://frank.pocnet.net/sheets/084/e/ECC81.pdf","https://frank.pocnet.net/sheets/093/1/12AT7.pdf"],"source_urls":{"r_type":"http://www.r-type.org/exhib/acf0106.htm","tdsl":"http://tdsl.duncanamps.com/show.php?des=A2900","radiomuseum":"https://www.radiomuseum.org/tubes/tube_a2900.html"},"raw_equivalents":["ECC81","12AT7","CV4024","CV455","CV6091","B152","B309","B739","ECC801S","E81CC","6201","6060","E2157","M8162","M8136"],"equivalents":[{"type_number":"12AT7","equivalence_type":"direct","notes":null}],"similar":[],"pins":[{"pin_number":"1","function":"Anode 2 (Triode section 2)","function_code":"a2","notes":null},{"pin_number":"2","function":"Control Grid 2 (Triode section 2)","function_code":"g1_2","notes":null},{"pin_number":"3","function":"Cathode 2 (Triode section 2)","function_code":"k2","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Heater","function_code":"h","notes":null},{"pin_number":"6","function":"Anode 1 (Triode section 1)","function_code":"a1","notes":null},{"pin_number":"7","function":"Control Grid 1 (Triode section 1)","function_code":"g1_1","notes":null},{"pin_number":"8","function":"Cathode 1 (Triode section 1)","function_code":"k1","notes":null},{"pin_number":"9","function":"Heater center tap","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":"Vh","display_name":"Heater Voltage","value":"6.3","numeric_value":"6.3","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.15","numeric_value":"0.15","unit":"A","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","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":"Ik_max","display_name":"Cathode Current (max)","value":"15","numeric_value":"15","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"90","numeric_value":"90","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":"-2","numeric_value":"-2","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"10","numeric_value":"10","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"10900","numeric_value":"10900","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"5.5","numeric_value":"5.5","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"60","numeric_value":"60","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"1.5","numeric_value":"1.5","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"2.2","numeric_value":"2.2","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"1.0","numeric_value":"1","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:35:16.443Z"}