{"type_number":"14A4","canonical_url":"https://tubeofile.com/tubes/14A4","manufacturer":null,"tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Loctal","description":"Medium-mu single triode in loctal (lock-in) construction. 12.6V heater version of the 7A4, designed for use as an amplifier, detector, or oscillator. Electrically similar to the 6J5/7A4 family. Designed for series-string heater circuits in AC/DC receivers.","is_directly_heated":false,"completeness":"high","notes":["12.6V heater version of the 7A4, with the same Loctal base and pinout. Heater current is 0.15A at 12.6V (vs 0.3A at 6.3V for the 7A4).","GE Essential Characteristics confirms: 12.6V/0.15A heater, Loctal (5AC) base, medium-mu triode, Pa_max=2.5W, Va_max=300V, Va=250V, Vg=-8V, Ia=9mA, ra=7700 ohms, gm=2600 umhos, mu=20.","Raytheon data shows slightly different test conditions: Va=250V, Vg=-12.5V, Ia=3.5mA, gm=2800 umhos, ra=8500 ohms — these may reflect a different operating point.","Brans Vademecum groups 14A4 with 6C4, 6C4W, 6CW4, 6FQ5, 7E5, EC70, and other medium-mu single triodes.","Designed for series-string heater chains in AC/DC radio and television receivers."],"references":["https://frank.pocnet.net/sheets/201/7/7A4.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=14A4","radiomuseum":"https://www.radiomuseum.org/tubes/tube_14a4.html"},"raw_equivalents":[],"equivalents":[],"similar":[{"type_number":"6C4","reason":"Similar single medium-mu triode but Noval base and 6.3V heater — different base and pinout","has_detail_page":true},{"type_number":"6J5GT","reason":"Electrically identical but Octal base and 6.3V heater — not pin-compatible","has_detail_page":false},{"type_number":"7A4","reason":"Electrically identical, same Loctal base and pinout, but 6.3V/0.3A heater — drop-in if heater supply is adapted","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Heater","function_code":"h","notes":null},{"pin_number":"2","function":"Plate","function_code":"a","notes":null},{"pin_number":"3","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"4","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"5","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"6","function":"Control Grid","function_code":"g1","notes":null},{"pin_number":"7","function":"Cathode","function_code":"k","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":"0.15","numeric_value":"0.15","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":"20","numeric_value":"20","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":"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":"4.0","numeric_value":"4","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"3.4","numeric_value":"3.4","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"3.0","numeric_value":"3","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:06:11.906Z"}