{"type_number":"800","canonical_url":"https://tubeofile.com/tubes/800","manufacturer":"RCA","tube_type_key":"power_triode","tube_type_display_name":"Power Triode","base_name":"UX4","description":"Directly heated transmitting triode with thoriated tungsten filament. Developed by RCA, first introduced October 1933. One of the early transmitting triodes capable of operation in the VHF range (full ratings to 60 MHz). Medium 4-pin bayonet base (UX4) with two top caps for plate and grid connections. Used in RF transmitters and audio amplifiers.","is_directly_heated":true,"completeness":"medium","notes":["DHT tube: the thoriated tungsten filament serves as the cathode; specified for AC or DC filament supply.","Both plate and grid connections are via top caps; base pins carry only filament.","Pa_max = 35W (CCS) for all services.","Class B AF push-pull (2 tubes): Va=750V, Vg=-55V, RL=6400 Ohm, Pout=90W; Va=1000V, Vg=-55V, RL=12500 Ohm, Pout=100W; Va=1250V, Vg=-70V, RL=21000 Ohm, Pout=106W.","Class B RF telephony (per tube, max mod. factor 1.0): Va=750V, Vg=-40V, Ia=45mA, Po=10W; Va=1000V, Vg=-55V, Ia=42mA, Po=14W.","Class C plate-modulated RF (per tube, max mod. factor 1.0): Va=750V, Vg=-150V, Ia=70mA, Po=35W; Va=1000V, Vg=-200V, Ia=70mA, Po=50W.","Class C key-down telegraphy (per tube): Va=750V, Vg=-100V, Ia=70mA, Po=35W; Va=1000V, Vg=-135V, Ia=70mA, Po=50W; Va=1250V, Vg=-175V, Ia=70mA, Po=65W.","Used in the first experimental radio-localization (radar) set designed by Ugo Tiberio in 1936 (100W output at 200 MHz)."],"references":["https://frank.pocnet.net/sheets/049/8/800.pdf","https://www.radiomuseum.org/tubes/tube_800.html"],"source_urls":{"r_type":null,"tdsl":null,"radiomuseum":"https://www.radiomuseum.org/tubes/tube_800.html"},"raw_equivalents":["VT-64","CV2657"],"equivalents":[],"similar":[{"type_number":"RK30","reason":"Normally replaceable transmitting triode per Radiomuseum; slightly different characteristics","has_detail_page":false}],"pins":[{"pin_number":"1","function":"Filament","function_code":"h","notes":null},{"pin_number":"2","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"3","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"4","function":"Filament","function_code":"h","notes":null},{"pin_number":"Cap P","function":"Plate (top cap)","function_code":"a","notes":null},{"pin_number":"Cap G","function":"Grid (top cap)","function_code":"g1","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"7.5","numeric_value":"7.5","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":"Va_max","display_name":"Anode Voltage (max)","value":"1250","numeric_value":"1250","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"35","numeric_value":"35","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"160","numeric_value":"160","unit":"mA","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"1000","numeric_value":"1000","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-55","numeric_value":"-55","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"28","numeric_value":"28","unit":"mA","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"15","numeric_value":"15","unit":"—","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"106","numeric_value":"106","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"21000","numeric_value":"21000","unit":"Ω","param_group":"output"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"2.5","numeric_value":"2.5","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"2.8","numeric_value":"2.8","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"0.8","numeric_value":"0.8","unit":"pF","param_group":"capacitances"},{"key":"freq","display_name":"Max Operating Frequency","value":"60","numeric_value":"60","unit":"MHz","param_group":"noise_rf"}]}],"synced_at":"2026-04-07T12:32:56.873Z"}