{"type_number":"7B7","canonical_url":"https://tubeofile.com/tubes/7B7","manufacturer":"Philco","tube_type_key":"ss_pentode","tube_type_display_name":"Small Signal Pentode","base_name":"Loctal","description":"Remote-cutoff RF pentode in loctal (lock-in) construction, designed for use as an RF or IF amplifier with automatic gain control. Lower heater current variant (0.15A) compared to the 7A7 (0.3A). Introduced by Philco in 1938, widely used in AC/DC radio receivers.","is_directly_heated":false,"completeness":"medium","notes":["Remote-cutoff (variable-mu) pentode for AGC-controlled RF/IF stages.","GE Essential Characteristics: Va=250V, Vg2=100V, Vg1=-3V gives Ia=8.5mA, Ig2=1.7mA, gm=1750 umhos, rp=750k ohms.","Max plate dissipation 2.35W, max plate voltage 300V, max screen voltage 100V (GE data).","Brans Vademecum lists extensive equivalents in table Vb including 12SK7, 6SK7, 6BD6, EF39, and many others — these are Octal/Noval base types and not pin-compatible Loctal drop-ins."],"references":["https://tdsl.duncanamps.com/show.php?des=7B7","https://www.radiomuseum.org/tubes/?tube=7B7"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=7B7","radiomuseum":"https://www.radiomuseum.org/tubes/tube_7b7.html"},"raw_equivalents":["CV522"],"equivalents":[],"similar":[{"type_number":"6BJ6","reason":"Successor type with improved characteristics","has_detail_page":true},{"type_number":"6SK7","reason":"Electrically similar remote-cutoff pentode but Octal base — not pin-compatible","has_detail_page":true},{"type_number":"6SS7","reason":"Different base (Octal) variant listed as equivalent in some references","has_detail_page":false},{"type_number":"7A7","reason":"Same Loctal pinout (8V) and remote-cutoff pentode but higher heater current (0.3A vs 0.15A) and different operating characteristics — Raytheon lists as substitute","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":"Screen Grid (g2)","function_code":"g2","notes":null},{"pin_number":"4","function":"Suppressor Grid (g3)","function_code":"g3","notes":null},{"pin_number":"5","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"6","function":"Control Grid (g1)","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":"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"}],"sections":[{"section_number":1,"section_label":"Remote-Cutoff Pentode","tube_type_key":"ss_pentode","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":"2.35","numeric_value":"2.35","unit":"W","param_group":"absolute_max"},{"key":"Vg2_max","display_name":"Screen Voltage (max)","value":"100","numeric_value":"100","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":"-3","numeric_value":"-3","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"8.5","numeric_value":"8.5","unit":"mA","param_group":"typical_operating"},{"key":"Vg2","display_name":"Screen Voltage","value":"100","numeric_value":"100","unit":"V","param_group":"typical_operating"},{"key":"mAg2","display_name":"Screen Current","value":"1.7","numeric_value":"1.7","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"750000","numeric_value":"750000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"1.75","numeric_value":"1.75","unit":"mA/V","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"0.007","numeric_value":"0.007","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"5","numeric_value":"5","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"6","numeric_value":"6","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:32:17.173Z"}