{"type_number":"6BL7","canonical_url":"https://tubeofile.com/tubes/6BL7","manufacturer":"RCA","tube_type_key":"power_triode","tube_type_display_name":"Power Triode","base_name":"Octal","description":"Medium-mu twin power triode with separate cathodes. Originally designed for vertical deflection in television receivers (525-line systems). Each section can dissipate 10 W. Low plate resistance (2150 ohms) and high transconductance (6.2 mA/V) make it suitable as a power driver or low-power output tube in audio circuits.","is_directly_heated":false,"completeness":"high","notes":["6BL7GT and 6BL7 are identical; the GT suffix denotes the glass-tubular envelope style.","6BL7GTA is a revised version with the same electrical characteristics but potentially tighter tolerances.","6BX7GT and 6DN7 are listed as substitutes in the Sams Tube Substitution Handbook but may not be exact equivalents in all circuits — verify ratings before substituting.","Tung-Sol datasheet (1950) rates mu=14, gm=7.0 mA/V, ra=2000 ohms; RCA (1953) rates mu=15, gm=6.2 mA/V, ra=2150 ohms. Both are within normal manufacturing spread.","No audio-specific load resistance or power output data in manufacturer datasheets — the tube was specified primarily for TV vertical deflection service.","Minimum cathode bias resistor per section is 220 ohms to protect against temporary failure of grid excitation."],"references":["https://frank.pocnet.net/sheets/049/6/6BL7GT.pdf","https://www.r-type.org/pdfs/6bl7gt.pdf"],"source_urls":{"r_type":"https://www.r-type.org/exhib/abh0123.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=6BL7GT","radiomuseum":"https://www.radiomuseum.org/tubes/tube_6bl7gt.html"},"raw_equivalents":["6BL7GT","6BL7-GT","6BL7GTA","CV5039"],"equivalents":[],"similar":[{"type_number":"6BX7GT","reason":"Similar pinout but different mu (10 vs 15) and ra (1300 vs 2150 ohms) — may not be a direct substitute in all circuits","has_detail_page":false},{"type_number":"6DN7","reason":"Listed as substitute in Sams handbook but different characteristics — verify ratings before substituting","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Grid (triode 1)","function_code":"g1_1","notes":null},{"pin_number":"2","function":"Anode (triode 1)","function_code":"a1","notes":null},{"pin_number":"3","function":"Cathode (triode 1)","function_code":"k1","notes":null},{"pin_number":"4","function":"Grid (triode 2)","function_code":"g1_2","notes":null},{"pin_number":"5","function":"Anode (triode 2)","function_code":"a2","notes":null},{"pin_number":"6","function":"Cathode (triode 2)","function_code":"k2","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","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":"1.5","numeric_value":"1.5","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode","tube_type_key":"power_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"500","numeric_value":"500","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"10","numeric_value":"10","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"60","numeric_value":"60","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"200","numeric_value":"200","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"4.7","numeric_value":"4.7","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":"-9","numeric_value":"-9","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"40","numeric_value":"40","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"2150","numeric_value":"2150","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"6.2","numeric_value":"6.2","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"15","numeric_value":"15","unit":"—","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"220","numeric_value":"220","unit":"Ω","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"4.2","numeric_value":"4.2","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"1.5","numeric_value":"1.5","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"4.4","numeric_value":"4.4","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"1.1","numeric_value":"1.1","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:18:33.148Z"}