{"type_number":"VT-25","canonical_url":"https://tubeofile.com/tubes/VT-25","manufacturer":"RCA","tube_type_key":"power_triode","tube_type_display_name":"Power Triode","base_name":"UX4","description":"Directly heated power triode, military designation for the type 10/10Y. Originally designed by RCA as the UX-210 in 1926 for audio-frequency amplification and oscillator use. Features thoriated tungsten filament and low mu (8) with exceptional linearity. Widely used as single-ended audio output tube and driver for larger triodes such as the 300B and 45.","is_directly_heated":true,"completeness":"high","notes":["VT-25 is the military designation for the type 10; 10Y is the uprated transmitter variant with higher plate dissipation (15W CW vs 10W for the type 10 in audio service).","Grid voltages in the RCA datasheet are referenced to the mid-point of the filament when operated on AC. If operated on DC, reduce each stated grid voltage by 5.0V and reference to the negative filament terminal.","VT-25A is a variant with oxide-coated filament instead of thoriated tungsten, drawing approximately the same heater current but with different emission characteristics. The two types are not always interchangeable.","The 1602 is a ruggedized military version; CV603 is the British military equivalent.","UX-210 and CX-310 are the original 1920s RCA and Cunningham designations respectively for the same tube in globe/balloon envelope."],"references":["https://frank.pocnet.net/sheets/021/1/10.pdf","https://frank.pocnet.net/sheets/049/1/10Y.pdf"],"source_urls":{"r_type":"http://www.r-type.org/exhib/aag0134.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=VT25","radiomuseum":"https://www.radiomuseum.org/tubes/tube_10y.html"},"raw_equivalents":["10","10Y","UX-210","CX-310","CV603","1602","VT-25A"],"equivalents":[{"type_number":"VT-25A","equivalence_type":"direct","notes":null}],"similar":[],"pins":[{"pin_number":"1","function":"Filament","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","function_code":"h","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":"1.25","numeric_value":"1.25","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":"425","numeric_value":"425","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"10","numeric_value":"10","unit":"W","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"425","numeric_value":"425","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-40","numeric_value":"-40","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"18","numeric_value":"18","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"5000","numeric_value":"5000","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","numeric_value":"8","unit":"—","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"2220","numeric_value":"2220","unit":"Ω","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"1.6","numeric_value":"1.6","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"10200","numeric_value":"10200","unit":"Ω","param_group":"output"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"7","numeric_value":"7","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"4","numeric_value":"4","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"3","numeric_value":"3","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T19:09:38.793Z"}