{"type_number":"6F5","canonical_url":"https://tubeofile.com/tubes/6F5","manufacturer":"RCA","tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Octal","description":"High-mu single triode designed for use as a voltage amplifier in resistance-coupled circuits. Indirectly heated unipotential cathode, Octal base with top-cap grid connection. Metal-shell envelope (MTT8A). Introduced by RCA in 1935; widely used in AC and AC-DC receivers. The grid was moved from the base to a top cap on 18 June 1935, distinguishing the 6F5 from its successor the 6SF5 (which has the grid on pin 3).","is_directly_heated":false,"completeness":"medium","notes":["The grid connection was moved from the Octal base to a top cap on 18 June 1935, creating the 6F5 as distinct from the earlier base-grid version and from the successor 6SF5.","Metal-shell envelope (MTT8A). Pin 1 (shell) is internally connected to the cathode — connect to cathode or circuit ground.","Maximum ratings and typical operating conditions are identical to the 6SF5. The RCA resistance-coupled amplifier chart published under Type 6SF5 applies to the 6F5 and 6F5-GT.","In circuits where the cathode is not directly connected to the heater, the heater-to-cathode voltage should be kept as low as possible (no discrete Vhk_max stated in the consulted datasheet).","The 6F5G is a glass-bulb (globe) variant and 6F5GT is the glass-GT variant — both electrically identical with the grid on a top cap. CV715, CV1908, CV1909, CV1910 are British military equivalents.","Pa_max not stated in the RCA 1947 or Raytheon 1945 datasheets consulted. At the typical operating point (Va=250V, Ia=0.9mA), anode dissipation is approximately 225mW."],"references":["https://frank.pocnet.net/sheets/049/6/6F5.pdf","https://frank.pocnet.net/sheets/049/6/6SF5.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=6F5","radiomuseum":"https://www.radiomuseum.org/tubes/tube_6f5.html"},"raw_equivalents":["6F5G","6F5GT","6F5MG","6F5M","CV1908","CV1909","CV1910","CV715","VT73"],"equivalents":[],"similar":[{"type_number":"12F5","reason":"Electrically identical 12.6V heater version — same mu, ra, gm, and pin topology but different heater voltage (12.6V vs 6.3V).","has_detail_page":false},{"type_number":"6SF5","reason":"Electrically identical (same mu=100, ra=66kΩ, gm=1.5mA/V) but different pinout — 6SF5 has grid on pin 3, 6F5 has grid on top cap. Not a drop-in replacement without rewiring.","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Metal Shell (internally connected to cathode)","function_code":"shell","notes":null},{"pin_number":"2","function":"Heater","function_code":"h","notes":null},{"pin_number":"3","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"4","function":"Plate","function_code":"a","notes":null},{"pin_number":"5","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"6","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","notes":null},{"pin_number":"8","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"TC","function":"Control Grid (top cap)","function_code":"g1","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":"Triode","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":"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":"66000","numeric_value":"66000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"1.5","numeric_value":"1.5","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"100","numeric_value":"100","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"2.4","numeric_value":"2.4","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"5.5","numeric_value":"5.5","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"4.0","numeric_value":"4","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-21T23:11:40.913Z"}