{"type_number":"19AJ8","canonical_url":"https://tubeofile.com/tubes/19AJ8","manufacturer":"Philips","tube_type_key":"triode_hexode","tube_type_display_name":"Triode-Hexode","base_name":"Noval","description":"Triode-heptode frequency converter in 9-pin miniature (Noval) construction with 19V series-string heater. Designed for use as a combined oscillator and mixer in FM/AM superheterodyne receivers. Electrically identical to the UCH81 and 19D8. The triode section serves as local oscillator; the heptode section as mixer.","is_directly_heated":false,"completeness":"high","notes":["19V/0.1A heater for series-string operation in AC/DC receivers (no transformer).","Valve Equivalents reference lists as 'Triode Heptode' with Noval (B9A) base.","UCH81 is the European designation for the identical tube with 'U' prefix indicating 100mA series heater.","Brans Vademecum table VIb cross-lists with ECH81, ECH83, and many other converter types."],"references":["https://tdsl.duncanamps.com/show.php?des=19AJ8","https://www.radiomuseum.org/tubes/?tube=19AJ8"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=19AJ8","radiomuseum":"https://www.radiomuseum.org/tubes/tube_19aj8.html"},"raw_equivalents":["UCH81","19D8"],"equivalents":[{"type_number":"UCH81","equivalence_type":"direct","notes":null}],"similar":[{"type_number":"12AJ8","reason":"Same structure but 12.6V heater — different series-string voltage","has_detail_page":false},{"type_number":"6AJ8","reason":"Same structure and Noval pinout but 6.3V heater — Brans lists in same group","has_detail_page":false},{"type_number":"6DS8","reason":"Brans lists in same group — similar triode-heptode converter","has_detail_page":true},{"type_number":"ECH81","reason":"Same triode-heptode structure and Noval pinout but 6.3V heater — not interchangeable in series-string circuits","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Heptode Signal Grid (g1h)","function_code":"g1h","notes":null},{"pin_number":"2","function":"Heptode Plate","function_code":"ah","notes":null},{"pin_number":"3","function":"Heptode Grids 2&4 (Screen)","function_code":"g2h","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":"Triode Plate","function_code":"at","notes":null},{"pin_number":"7","function":"Triode Grid","function_code":"g1t","notes":null},{"pin_number":"8","function":"Cathode (Common)","function_code":"k","notes":null},{"pin_number":"9","function":"Internal Shield","function_code":"is","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"19","numeric_value":"19","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.1","numeric_value":"0.1","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode (Oscillator)","tube_type_key":"small_signal_triode","specs":[{"key":"Va","display_name":"Anode Voltage (typical)","value":"100","numeric_value":"100","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"9","numeric_value":"9","unit":"mA","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"5.5","numeric_value":"5.5","unit":"mA/V","param_group":"typical_operating"}]},{"section_number":2,"section_label":"Heptode (Mixer)","tube_type_key":"hexode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Vg2_max","display_name":"Screen Voltage (max)","value":"150","numeric_value":"150","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":"Vg2","display_name":"Screen Voltage","value":"100","numeric_value":"100","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"3","numeric_value":"3","unit":"mA","param_group":"typical_operating"},{"key":"mAg2","display_name":"Screen Current","value":"6.5","numeric_value":"6.5","unit":"mA","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"0.65","numeric_value":"0.65","unit":"mA/V","param_group":"typical_operating"}]}],"synced_at":"2026-04-07T12:06:39.232Z"}