{"type_number":"6C4","canonical_url":"https://tubeofile.com/tubes/6C4","manufacturer":null,"tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"B7G","description":"Miniature medium-mu triode suitable for general-purpose applications. Especially useful as a local oscillator in high-frequency and VHF receiver circuits. Low capacitances and lead inductances make it attractive for RF use and series-heater circuits.","is_directly_heated":false,"completeness":"high","notes":["The 6C4 is electrically one half of a 12AU7 (ECC82). The electrode structure is identical, making it useful as a reference when comparing single vs. dual triode designs.","Plate is connected to both pins 1 and 5 for reduced lead inductance at VHF — both pins must be connected in the circuit.","Pin 2 is an internal connection (internal shield) — do not ground or connect externally unless using an external shield per EIA 316.","Grid-circuit resistance limits differ by bias method: 0.25 MΩ max with fixed bias, 1.0 MΩ max with cathode bias.","First registered May 9, 1942, developed by RCA. Predecessor to this socket type was the 6L5G (octal).","5744 (WA, WB) and 1201 are ruggedized military versions with identical pinout (Brans Vademecum).","Raytheon (1945) lists 6J5GT/G and 6L5G as substitutes — these are octal-base triodes, not pin-compatible with the B7G 6C4."],"references":["https://tube-data.com/sheets/093/6/6C4.pdf","https://tube-data.com/sheets/127/6/6C4.pdf","https://www.r-type.org/pdfs/6c4.pdf"],"source_urls":{"r_type":"https://www.r-type.org/exhib/aaa0038.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=6C4","radiomuseum":"https://www.radiomuseum.org/tubes/tube_6c4.html"},"raw_equivalents":["EC90","CV133","CV852","M8080","6100","6135","L77","5744","1201","7E5","QA2401","6C4W","6C4WA"],"equivalents":[],"similar":[],"pins":[{"pin_number":"1","function":"Plate","function_code":"a","notes":null},{"pin_number":"2","function":"Internal Connection","function_code":"ia","notes":null},{"pin_number":"3","function":"Heater","function_code":"h","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Plate","function_code":"a","notes":null},{"pin_number":"6","function":"Grid","function_code":"g1","notes":null},{"pin_number":"7","function":"Cathode","function_code":"k","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":"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":"3.5","numeric_value":"3.5","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"25","numeric_value":"25","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"100","numeric_value":"100","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"1.0","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":"-8.5","numeric_value":"-8.5","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"10.5","numeric_value":"10.5","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":"2.2","numeric_value":"2.2","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"17","numeric_value":"17","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"1.6","numeric_value":"1.6","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"1.8","numeric_value":"1.8","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"1.3","numeric_value":"1.3","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:19:22.447Z"}