{"type_number":"EF80","canonical_url":"https://tubeofile.com/tubes/EF80","manufacturer":"Philips","tube_type_key":"ss_pentode","tube_type_display_name":"Small Signal Pentode","base_name":"Noval","description":"RF pentode intended for use as R.F., I.F. or video amplifying tube or as mixing tube in television receivers. High transconductance with low interelectrode capacitances make it suitable for wideband IF amplifiers, video amplifiers, self-oscillating mixers, and sync separator circuits.","is_directly_heated":false,"completeness":"high","notes":["Cathode is brought out to two pins (pins 1 and 3) to reduce input impedance degradation at high frequencies. For input impedance measurements and optimal RF performance, both cathode pins must be connected to the input return; output circuit should connect to the other cathode pin.","Fixed bias is not recommended by Tesla datasheet. When using grid leak resistor of 0.2 MΩ, it is insufficient to develop the required negative bias — cathode bias resistor is needed.","Suppressor grid (g3) is brought out to a separate pin (pin 9) and is internally connected in the standard Noval base arrangement. Must be connected to cathode externally.","When used as video amplifier, gain between control grid input and cathode ray tube input should not exceed 25 to prevent microphonic effects.","Rg_max depends on bias method: 0.5 MΩ for fixed bias, 1 MΩ for cathode (self) bias.","Triode-strapped data sourced from Tom Schlangen 'Pentodes Strapped as Triodes' (2009 measured data table), not from the manufacturer datasheet."],"references":["https://frank.pocnet.net/sheets/010/e/EF80.pdf","https://frank.pocnet.net/sheets/020/e/EF80.pdf","https://tube-data.com/sheets/183/e/EF80.pdf","http://www.audiodesignguide.com/New2A3/ETF06TS.pdf"],"source_urls":{"r_type":"https://www.r-type.org/exhib/aaa0008.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=EF80","radiomuseum":"https://www.radiomuseum.org/tubes/tube_ef80.html"},"raw_equivalents":["6BX6","Z719","CV1376"],"equivalents":[],"similar":[{"type_number":"EF800","reason":"Special quality version of EF80 with tighter tolerances — electrically equivalent, drop-in compatible, but selected for professional use","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Cathode","function_code":"k","notes":null},{"pin_number":"2","function":"Control Grid (g1)","function_code":"g1","notes":null},{"pin_number":"3","function":"Cathode","function_code":"k","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Heater","function_code":"h","notes":null},{"pin_number":"6","function":"Internal Shield","function_code":"ia","notes":null},{"pin_number":"7","function":"Anode","function_code":"a","notes":null},{"pin_number":"8","function":"Screen Grid (g2)","function_code":"g2","notes":null},{"pin_number":"9","function":"Suppressor Grid (g3)","function_code":"g3","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":"Pentode","tube_type_key":"ss_pentode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"2.5","numeric_value":"2.5","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":"15","numeric_value":"15","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"150","numeric_value":"150","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"1","numeric_value":"1","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"200","numeric_value":"200","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"200","numeric_value":"200","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-2.55","numeric_value":"-2.55","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"10","numeric_value":"10","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"2.6","numeric_value":"2.6","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"550000","numeric_value":"550000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"7.1","numeric_value":"7.1","unit":"mA/V","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"<0.007","numeric_value":null,"unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"<0.012","numeric_value":null,"unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"6.9","numeric_value":"6.9","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"3.1","numeric_value":"3.1","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"μg2/g1 (Amplification Factor)","value":"50","numeric_value":"50","unit":"—","param_group":null},{"key":null,"display_name":"Vs_max (cold, no signal)","value":"550","numeric_value":"550","unit":"V","param_group":null},{"key":null,"display_name":"Req (Equivalent Noise Resistance)","value":"1100","numeric_value":"1100","unit":"Ω","param_group":null},{"key":null,"display_name":"Va_max (cold, no signal)","value":"550","numeric_value":"550","unit":"V","param_group":null}]},{"section_number":2,"section_label":"Triode Strapped","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":"2.5","numeric_value":"2.5","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"15","numeric_value":"15","unit":"mA","param_group":"absolute_max"},{"key":"ra","display_name":"Anode Resistance","value":"8000","numeric_value":"8000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"5.0","numeric_value":"5","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"40","numeric_value":"40","unit":"—","param_group":"typical_operating"}]}],"synced_at":"2026-04-07T12:41:23.648Z"}