{"type_number":"242C","canonical_url":"https://tubeofile.com/tubes/242C","manufacturer":"Western Electric","tube_type_key":"power_triode","tube_type_display_name":"Power Triode","base_name":"Jumbo4","description":"Directly-heated thoriated-tungsten filament transmitting triode with air cooling. Uses a Jumbo 4-pin bayonet base. A redesign of the 242A with a new metal plate construction, retaining the same 100W plate dissipation as the 211. Manufactured by Western Electric, Westinghouse, GE, Amperex, STC, and NEC among others. Designed for RF oscillator, RF amplifier, AF amplifier, and modulator service.","is_directly_heated":true,"completeness":"low","notes":["DHT tube: the thoriated-tungsten filament serves as the cathode; there is no heater-cathode isolation.","The Jumbo 4-pin bayonet base (RCA basing 4AZ) is the same large base used on the 211 and 845.","ML-242C is the Westinghouse designation; GL-242C is the GE designation.","Radiomuseum notes: '242A with redesigned metal plate, retaining the same 100W dissipation as 211.'","Pa_max is 100W for Class B and Class C service; derate for Class A₁ CCS operation (typically 75W, same as 211).","Requires careful attention to filament supply — AC operation is standard for transmitting service."],"references":["https://tdsl.duncanamps.com/show.php?des=242C","https://www.radiomuseum.org/tubes/?tube=242C"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=242C","radiomuseum":"https://www.radiomuseum.org/tubes/tube_242c.html"},"raw_equivalents":["ML-242C","GL-242C","CV2587"],"equivalents":[],"similar":[{"type_number":"211","reason":"Same filament (10V/3.25A), same base, same 100W Pa (Class B/C) and mu (~12) — the 242C is essentially a 242A redesign in the same performance class as the 211 but with a different plate structure","has_detail_page":true},{"type_number":"242A","reason":"Earlier version with original plate design — same electrical ratings but different physical construction","has_detail_page":false},{"type_number":"242B","reason":"Variant in the 242 family — different plate rating or construction details","has_detail_page":false}],"pins":[{"pin_number":"1","function":"Grid","function_code":"g1","notes":null},{"pin_number":"2","function":"Filament (f+)","function_code":"h","notes":null},{"pin_number":"3","function":"Plate (Anode)","function_code":"a","notes":null},{"pin_number":"4","function":"Filament (f-)","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"10","numeric_value":"10","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"3.25","numeric_value":"3.25","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode","tube_type_key":"power_triode","specs":[{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"100","numeric_value":"100","unit":"W","param_group":"absolute_max"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"12","numeric_value":"12","unit":"—","param_group":"typical_operating"}]}],"synced_at":"2026-04-07T12:07:41.557Z"}