{"type_number":"1625","canonical_url":"https://tubeofile.com/tubes/1625","manufacturer":"Tung-Sol","tube_type_key":"beam_tetrode","tube_type_display_name":"Beam Tetrode","base_name":"UX7","description":"Transmitting beam power amplifier with 12.6V heater, designed for military vehicular and aircraft radio service. Electrically similar to the 807 but with a 12.6V heater (vs 6.3V) and a 7-pin UX7 base (vs 5-pin UX5). Top-cap plate connection. Manufactured by Tung-Sol, RCA, Sylvania, and others under JAN specifications.","is_directly_heated":false,"completeness":"medium","notes":["The 1625 is the 12.6V heater military version of the 807. Electrically identical except for heater voltage and base type.","Uses a 7-pin UX7 base with a top-cap plate connection. The 807 uses a 5-pin UX5 base — the two are NOT interchangeable without an adapter.","TDSL and ARRL references list RF Class C, Class B, and AB1 operating conditions. Primary use was in military AN/ARC-5 command set transmitters.","Widely available as war surplus; commonly adapted for amateur radio transmitter use at 12.6V mobile supply.","Datasheet capacitances measured with external shield: Cgk=11pF, Cak=7pF, Cgp=0.2pF."],"references":["https://frank.pocnet.net/sheets/127/1/1625.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=1625","radiomuseum":"https://www.radiomuseum.org/tubes/tube_1625.html"},"raw_equivalents":["CV659","VT136"],"equivalents":[],"similar":[{"type_number":"807","reason":"Same electrical characteristics but 6.3V/0.9A heater on UX5 base — different base and heater voltage, not pin-compatible","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Control Grid (g1)","function_code":"g1","notes":null},{"pin_number":"2","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"3","function":"Heater","function_code":"h","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Cathode","function_code":"k","notes":null},{"pin_number":"6","function":"Screen Grid (g2)","function_code":"g2","notes":null},{"pin_number":"7","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"TC","function":"Plate (top cap)","function_code":"a","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"12.6","numeric_value":"12.6","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.45","numeric_value":"0.45","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Beam Tetrode","tube_type_key":"beam_tetrode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"750","numeric_value":"750","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"350","numeric_value":"350","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"30","numeric_value":"30","unit":"W","param_group":"absolute_max"},{"key":"Ps_max","display_name":"Screen Dissipation (max)","value":"3.5","numeric_value":"3.5","unit":"W","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"0.01","numeric_value":"0.01","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"600","numeric_value":"600","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"200","numeric_value":"200","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-90","numeric_value":"-90","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"100","numeric_value":"100","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"10","numeric_value":"10","unit":"mA","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"50","numeric_value":"50","unit":"W","param_group":"output"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"0.2","numeric_value":"0.2","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"11","numeric_value":"11","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"7","numeric_value":"7","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T19:00:58.889Z"}