{"type_number":"6FM7","canonical_url":"https://tubeofile.com/tubes/6FM7","manufacturer":"General Electric","tube_type_key":"compound","tube_type_display_name":"Compound (multi-section)","base_name":"Compactron","description":"Compactron dissimilar double triode designed for use as a combined vertical-deflection oscillator and amplifier in television receivers. Section 1 is a high-mu triode for oscillator service; Section 2 is a low-mu, high-perveance triode for amplifier service.","is_directly_heated":false,"completeness":"high","notes":["13FM7 and 15FM7 are identical to 6FM7 except for heater ratings (series-string variants) and are not pin-for-pin replacements in parallel-heater circuits.","Section 2 has two grid pins (pins 3 and 8) which must both be connected to the grid circuit.","Pin 6 is an internal connection and must not be used.","Originally designed for TV vertical deflection; the low-mu Section 2 is popular in DIY audio as a low-power single-ended output triode (approx. 1–1.5 W).","Section 2 grid voltage of 0 V at Va=60 V, Ia=95 mA is rated for short interval only (2 seconds max) to avoid tube damage.","In stages operating with grid-leak bias, an adequate cathode-bias resistor or other suitable means is required to protect the tube in the absence of excitation."],"references":["https://frank.pocnet.net/sheets/123/6/6FM7.pdf","https://frank.pocnet.net/sheets/049/6/6FM7.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=6FM7","radiomuseum":"https://www.radiomuseum.org/tubes/tube_6fm7.html"},"raw_equivalents":["13FM7","15FM7"],"equivalents":[],"similar":[{"type_number":"6DE7","reason":"Dissimilar double triode Compactron for TV vertical deflection — same base type but different electrical characteristics","has_detail_page":true},{"type_number":"6EM7","reason":"Dissimilar double triode Compactron for TV vertical deflection — same application but different mu/gm characteristics","has_detail_page":true},{"type_number":"6EW7","reason":"Dissimilar double triode Compactron for TV vertical deflection — same base type but different electrical characteristics","has_detail_page":true},{"type_number":"6GF7","reason":"Dissimilar double triode Compactron for TV vertical deflection — same base type but different electrical characteristics","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Heater","function_code":"h","notes":null},{"pin_number":"2","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"3","function":"Grid (Section 2)","function_code":"g1_2","notes":null},{"pin_number":"4","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"5","function":"Plate (Section 2)","function_code":"a2","notes":null},{"pin_number":"6","function":"Internal Connection — Do Not Use","function_code":"ia","notes":null},{"pin_number":"7","function":"Cathode (Section 2)","function_code":"k2","notes":null},{"pin_number":"8","function":"Grid (Section 2)","function_code":"g1_2","notes":null},{"pin_number":"9","function":"Cathode (Section 1)","function_code":"k1","notes":null},{"pin_number":"10","function":"Grid (Section 1)","function_code":"g1_1","notes":null},{"pin_number":"11","function":"Plate (Section 1)","function_code":"a1","notes":null},{"pin_number":"12","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":"1.05","numeric_value":"1.05","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode 1 (High-Mu Oscillator)","tube_type_key":"small_signal_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"350","numeric_value":"350","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"1.0","numeric_value":"1","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"50","numeric_value":"50","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":"2.2","numeric_value":"2.2","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":"-3","numeric_value":"-3","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"2.0","numeric_value":"2","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"30000","numeric_value":"30000","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":"66","numeric_value":"66","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"4.0","numeric_value":"4","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"2.4","numeric_value":"2.4","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"0.4","numeric_value":"0.4","unit":"pF","param_group":"capacitances"}]},{"section_number":2,"section_label":"Triode 2 (Low-Mu Amplifier)","tube_type_key":"power_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"550","numeric_value":"550","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 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Resistance","value":"920","numeric_value":"920","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"6.0","numeric_value":"6","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"5.5","numeric_value":"5.5","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"7.0","numeric_value":"7","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"7.0","numeric_value":"7","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"1.1","numeric_value":"1.1","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"Peak Positive Pulse Plate Voltage","value":"1500","numeric_value":"1500","unit":"V","param_group":null}]}],"synced_at":"2026-04-07T12:23:42.875Z"}