{"type_number":"C3g","canonical_url":"https://tubeofile.com/tubes/C3g","manufacturer":"Siemens & Halske / Telefunken","tube_type_key":"ss_pentode","tube_type_display_name":"Small Signal Pentode","base_name":"Loctal","description":"Frame-grid pentode for wideband amplifiers (Breitbandverstärker). Developed for the German Federal Post Office (Deutsche Bundespost) telecommunications equipment. Low-noise, high-transconductance design with tight tolerances, special cathode free from interface effects, and guaranteed long life (>10,000 hours).","is_directly_heated":false,"completeness":"high","notes":["C3g/s is a selected variant where transconductance exceeds 105% of nominal (≥14.7 mA/V).","Ua max of 220V is the operating limit; the no-signal supply voltage (Uao) may be up to 550V. Similarly Ug2o max is 550V but operating Ug2 max is 220V.","Both cathode pins (5 and 7) must be connected in parallel.","The metal screening can connects to the base center spigot (pin m) and should be grounded for proper shielding.","Heater voltage must be held within ±5% for guaranteed lifetime ratings to apply.","Loctal base with continental key socket — not pin-compatible with standard B8G/Loctal American types despite similar appearance."],"references":["https://frank.pocnet.net/sheets/128/c/C3g.pdf","https://frank.pocnet.net/sheets/190/c/C3g.pdf","https://www.jacmusic.com/techcorner/ARTICLES/English/Portraits/C3g/C3g-C3m-info.html"],"source_urls":{"r_type":"https://www.r-type.org/exhib/aai0324.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=C3g","radiomuseum":"https://www.radiomuseum.org/tubes/tube_c3g.html"},"raw_equivalents":["C3g/s","CV10522"],"equivalents":[],"similar":[{"type_number":"5A/152M","reason":"STC coaxial repeater pentode with similar characteristics and application — different Loctal base variant (B8G), not pin-compatible with C3g continental Loctal","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Heater","function_code":"h","notes":null},{"pin_number":"2","function":"Suppressor Grid (g3) + Shield","function_code":"g3","notes":null},{"pin_number":"3","function":"Anode","function_code":"a","notes":null},{"pin_number":"4","function":"Screen Grid (g2)","function_code":"g2","notes":null},{"pin_number":"5","function":"Cathode","function_code":"k","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":"0.37","numeric_value":"0.37","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Pentode","tube_type_key":"ss_pentode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"220","numeric_value":"220","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"220","numeric_value":"220","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":"Ps_max","display_name":"Screen Dissipation (max)","value":"0.7","numeric_value":"0.7","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"30","numeric_value":"30","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"120","numeric_value":"120","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"0.5","numeric_value":"0.5","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"220","numeric_value":"220","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"150","numeric_value":"150","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-4.5","numeric_value":"-4.5","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"13","numeric_value":"13","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"3.3","numeric_value":"3.3","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"300000","numeric_value":"300000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"14","numeric_value":"14","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"41","numeric_value":"41","unit":"—","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"115","numeric_value":"115","unit":"Ω","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"0.012","numeric_value":"0.012","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"5.5","numeric_value":"5.5","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"0.008","numeric_value":"0.008","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"9.5","numeric_value":"9.5","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"3.5","numeric_value":"3.5","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"No-signal Screen Supply Voltage (max)","value":"550","numeric_value":"550","unit":"V","param_group":null},{"key":null,"display_name":"Equivalent Anode Load Resistance (RiL)","value":"1.7","numeric_value":"1.7","unit":"kΩ","param_group":null},{"key":null,"display_name":"Grid 1 Dissipation (max)","value":"50","numeric_value":"50","unit":"mW","param_group":null},{"key":null,"display_name":"Equivalent Noise Resistance (Raeq)","value":"650","numeric_value":"650","unit":"Ω","param_group":null},{"key":null,"display_name":"Heater-Cathode Resistance (max)","value":"20","numeric_value":"20","unit":"kΩ","param_group":null},{"key":null,"display_name":"Max Envelope 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Resistance","value":"2300","numeric_value":"2300","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"17","numeric_value":"17","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"40","numeric_value":"40","unit":"—","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"180","numeric_value":"180","unit":"Ω","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"2.7","numeric_value":"2.7","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"7","numeric_value":"7","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"6","numeric_value":"6","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"Equivalent Noise Resistance 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