{"type_number":"VT127A","canonical_url":"https://tubeofile.com/tubes/VT127A","manufacturer":"Eimac","tube_type_key":"power_triode","tube_type_display_name":"Power Triode","base_name":null,"description":"Directly heated transmitting triode with thoriated tungsten filament, designed for VHF pulse oscillator and Class C RF amplifier service","is_directly_heated":true,"completeness":"low","notes":["The VT127A is the military designation for the Eimac 100TS (also designated 3-100D2). Used in WWII SCR-268 radar as a ring oscillator.","No standard socket base — connections are made via external rods protruding through the glass envelope: two top rods (plate, in parallel), two middle rods (grid, in parallel), two bottom rods (filament).","Class C operating data: Va=2000V, Ia=210mA, Vg=-340V, Pout≈300W. These are transmitter/RF amplifier conditions, not audio operating points.","Maximum plate dissipation is 100W continuous. For audio Class A use, plate voltage and current must be derated accordingly.","Transconductance (gm) and plate resistance (ra) not found in available sources; only mu=15.5 is confirmed. ra can be approximated as mu/gm when gm is measured at the operating point.","No standard catalog base — VT127A is an Eimac/Western Electric doorknob-style transmitting triode with 4 side rods (2 plate top, 2 grid middle, in parallel pairs) and 2 bottom filament rods. No conventional socket. Skipped by /roll scan."],"references":["https://vinylsavor.blogspot.com/2022/06/tube-of-month-vt127a.html","https://www.r-type.org/exhib/aaa1126.htm","https://www.radiomuseum.org/tubes/tube_vt127a.html","https://www.radiomuseum.org/tubes/tube_100ts.html"],"source_urls":{"r_type":"https://www.r-type.org/exhib/aaa1126.htm","tdsl":null,"radiomuseum":"https://www.radiomuseum.org/tubes/tube_vt127a.html"},"raw_equivalents":["100TS","3-100D2"],"equivalents":[],"similar":[],"pins":[{"pin_number":"top-1","function":"Plate (rod 1)","function_code":"a","notes":null},{"pin_number":"top-2","function":"Plate (rod 2, in parallel with top-1)","function_code":"a","notes":null},{"pin_number":"mid-1","function":"Control Grid (rod 1)","function_code":"g1","notes":null},{"pin_number":"mid-2","function":"Control Grid (rod 2, in parallel with mid-1)","function_code":"g1","notes":null},{"pin_number":"bot-1","function":"Filament (rod 1)","function_code":"h","notes":null},{"pin_number":"bot-2","function":"Filament (rod 2)","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"5","numeric_value":"5","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"10.5","numeric_value":"10.5","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":"2000","numeric_value":"2000","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"100","numeric_value":"100","unit":"W","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"2000","numeric_value":"2000","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-340","numeric_value":"-340","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"210","numeric_value":"210","unit":"mA","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"15.5","numeric_value":"15.5","unit":"—","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"300","numeric_value":"300","unit":"W","param_group":"output"}]}],"synced_at":"2026-04-07T19:09:46.815Z"}