{"type_number":"7AF7","canonical_url":"https://tubeofile.com/tubes/7AF7","manufacturer":"Sylvania","tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Loctal","description":"Medium-mu twin triode in loctal (lock-in) construction. Designed for use as a phase inverter or voltage amplifier. Electrically similar to the 7N7 but with lower mu (16 vs 20), lower transconductance, and lower heater current (0.3A vs 0.6A). Registered November 1944.","is_directly_heated":false,"completeness":"high","notes":["Sylvania rated the nominal heater voltage at 7.0V in the ratings section, though the typical operating voltage is 6.3V as with all loctal types. Heater current is 0.320A per Sylvania, though other sources list 0.300A.","The 14AF7 (also designated XXD) is the 12.6V/0.15A series-string heater version. Pin functions are identical.","The Sams Tube Substitution Handbook No. 16 lists 7N7 and 7AF7 as substitutes for each other, but only for parallel-filament circuits (marked with asterisk). The different heater current (0.3A vs 0.6A) makes them incompatible in series-string heater circuits.","Compared to the 7N7, the 7AF7 has somewhat lower interelectrode capacitances, which may be desirable in applications that do not require the higher mutual conductance of the 7N7."],"references":["https://frank.pocnet.net/sheets/084/7/7AF7.pdf"],"source_urls":{"r_type":"https://www.r-type.org/exhib/aaa1139.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=7AF7","radiomuseum":"https://www.radiomuseum.org/tubes/tube_7af7.html"},"raw_equivalents":["14AF7","12AH7GT"],"equivalents":[],"similar":[{"type_number":"12AU7","reason":"Radiomuseum lists as successor; similar medium-mu twin triode but Noval (9-pin) base","has_detail_page":true},{"type_number":"6SN7GT","reason":"Similar electricals to 7N7 family but Octal base — requires adapter or rewiring","has_detail_page":false},{"type_number":"7N7","reason":"Same Loctal base and identical pinout but higher mu (20 vs 16), higher gm (2.6 vs 2.1 mA/V), and different heater current (0.6A vs 0.3A)","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Heater","function_code":"h","notes":null},{"pin_number":"2","function":"Cathode (section 2)","function_code":"k2","notes":null},{"pin_number":"3","function":"Anode (section 2)","function_code":"a2","notes":null},{"pin_number":"4","function":"Control Grid (section 2)","function_code":"g1_2","notes":null},{"pin_number":"5","function":"Control Grid (section 1)","function_code":"g1_1","notes":null},{"pin_number":"6","function":"Anode (section 1)","function_code":"a1","notes":null},{"pin_number":"7","function":"Cathode (section 1)","function_code":"k1","notes":null},{"pin_number":"8","function":"Heater","function_code":"h","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":"0.32","numeric_value":"0.32","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":"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":"-10","numeric_value":"-10","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"9.0","numeric_value":"9","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"7600","numeric_value":"7600","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"2.1","numeric_value":"2.1","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"16","numeric_value":"16","unit":"—","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"1100","numeric_value":"1100","unit":"Ω","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"2.3","numeric_value":"2.3","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":"1.6","numeric_value":"1.6","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:31:57.193Z"}