{"type_number":"7B6","canonical_url":"https://tubeofile.com/tubes/7B6","manufacturer":"Tung-Sol","tube_type_key":"compound","tube_type_display_name":"Compound (multi-section)","base_name":"Loctal","description":"Duplex-diode high-mu triode in loctal (lock-in) construction, consisting of two diodes and a high-mu triode with a common cathode. Designed for use as a diode detector, AVC rectifier, and impedance or resistance coupled amplifier. Ratings and characteristics similar to the 6SQ7GT. Manufactured by Tung-Sol, introduced 1940.","is_directly_heated":false,"completeness":"high","notes":["Nominal heater voltage is 7.0V; typical operating heater voltage is 6.3V.","The triode section has mu=100 and rp=91000 ohms — high-mu design for voltage amplification.","Minimum diode current per plate: 0.8 mA at 10V DC applied.","Maximum plate voltage rating: 250V.","Tung-Sol datasheet (August 1940) used for specifications."],"references":["https://frank.pocnet.net/sheets/127/7/7B6.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=7B6","radiomuseum":"https://www.radiomuseum.org/tubes/tube_7b6.html"},"raw_equivalents":[],"equivalents":[],"similar":[{"type_number":"6SQ7GT","reason":"Electrically similar duplex-diode high-mu triode but Octal base — not pin-compatible with Loctal","has_detail_page":false},{"type_number":"75","reason":"Predecessor type with similar function (duplex-diode triode) but Octal base","has_detail_page":false},{"type_number":"7C6","reason":"Sams lists as substitute — similar Loctal duplex-diode triode","has_detail_page":false},{"type_number":"7C8","reason":"Raytheon lists as substitute — Loctal duplex-diode triode with different characteristics","has_detail_page":false}],"pins":[{"pin_number":"1","function":"Heater","function_code":"h","notes":null},{"pin_number":"2","function":"Plate (Triode)","function_code":"a","notes":null},{"pin_number":"3","function":"Diode Plate #1","function_code":"d1","notes":null},{"pin_number":"4","function":"Diode Plate #2","function_code":"d2","notes":null},{"pin_number":"5","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"6","function":"Control Grid (Triode)","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":"0.3","numeric_value":"0.3","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"High-Mu Triode","tube_type_key":"small_signal_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"250","numeric_value":"250","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"0.5","numeric_value":"0.5","unit":"W","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":"-2","numeric_value":"-2","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"0.9","numeric_value":"0.9","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"91000","numeric_value":"91000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"1.1","numeric_value":"1.1","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"100","numeric_value":"100","unit":"—","param_group":"typical_operating"}]},{"section_number":2,"section_label":"Diode Units (x2)","tube_type_key":"diode","specs":[{"key":"mAa_min","display_name":"Minimum Diode Current","value":"0.8","numeric_value":"0.8","unit":"mA","param_group":"typical_operating"}]}],"synced_at":"2026-04-07T12:32:11.761Z"}