{"type_number":"UX112A","canonical_url":"https://tubeofile.com/tubes/UX112A","manufacturer":null,"tube_type_key":"power_triode","tube_type_display_name":"Power Triode","base_name":"UX4","description":"Directly heated triode designed as a detector and audio-frequency amplifier for battery-operated receivers. Improved storage battery tube with oxide-coated filament, sensitive as detector and excellent as AF amplifier. The 'UX' prefix denotes the UX4 base; also designated 112A, 12A, and CX-112-A (Cunningham).","is_directly_heated":true,"completeness":"medium","notes":["One of the earliest oxide-coated filament triodes, introduced in the mid-1920s. The 112A superseded the original type 112 with improved characteristics.","The UX prefix denotes the UX4 base; later manufacturing dropped the prefix, designating it simply as 112A or 12A.","Cunningham marketed the same tube as CX-112-A.","Filament may be operated from a 6V storage battery with a suitable series resistor to reduce voltage to 5.0V at the socket terminals.","As a detector: recommended plate voltage 45V with grid leak and condenser bias. Grid leak 0.25 to 5 MΩ with 0.00025 µF grid condenser.","As an amplifier at Va=135V: Pout=115 mW into 8700 Ω load. At Va=180V (max): Pout=260 mW into 10800 Ω load.","When substituted for the 01A in radio-frequency circuits, neutralizing condensers or grid suppressor resistors may need adjustment to prevent oscillation."],"references":["https://frank.pocnet.net/sheets/029/1/112A.pdf","https://www.r-type.org/exhib/aab0104.htm"],"source_urls":{"r_type":"https://www.r-type.org/exhib/aab0104.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=112A","radiomuseum":"https://www.radiomuseum.org/tubes/tube_ux112a.html"},"raw_equivalents":["112A","12A","CV907","G112","PX1120"],"equivalents":[{"type_number":"12A","equivalence_type":"direct","notes":null}],"similar":[{"type_number":"01A","reason":"Contemporary DHT triode on UX4 base with 5V filament, similar mu (8) but higher ra (15000 Ω) and lower gm — used in similar applications but different operating characteristics","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Filament (f+)","function_code":"h","notes":null},{"pin_number":"2","function":"Plate","function_code":"a","notes":null},{"pin_number":"3","function":"Grid","function_code":"g1","notes":null},{"pin_number":"4","function":"Filament (f-)","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"5.0","numeric_value":"5","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.25","numeric_value":"0.25","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":"180","numeric_value":"180","unit":"V","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"135","numeric_value":"135","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-9","numeric_value":"-9","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"6.2","numeric_value":"6.2","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"5300","numeric_value":"5300","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"1.6","numeric_value":"1.6","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"8.5","numeric_value":"8.5","unit":"—","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"0.115","numeric_value":"0.115","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"8700","numeric_value":"8700","unit":"Ω","param_group":"output"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"8.1","numeric_value":"8.1","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"4.2","numeric_value":"4.2","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"2.1","numeric_value":"2.1","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:52:57.097Z"}