{"type_number":"25DK3","canonical_url":"https://tubeofile.com/tubes/25DK3","manufacturer":"General Electric","tube_type_key":"rectifier","tube_type_display_name":"Rectifier","base_name":"Noval","description":"Half-wave vacuum rectifier (heater-cathode type diode) designed for service as the damping diode in horizontal-deflection circuits of color television receivers. Features a unique heater-cathode insulating system enabling a peak rating of 6500V. Noval (B9A) 9-pin base with top cap connection to cathode.","is_directly_heated":false,"completeness":"high","notes":["General Electric Product Information datasheet, page 3-73. T-9 glass envelope, Base E9-89 (Button 9-Pin), Top Cap C1-2 (skirted miniature). Basing diagram EIA 9SG.","Designed specifically for color TV applications requiring higher PIV than standard B&W damper diodes.","Pin 1 is heater insulation coil. Pin 6 and Pin 8 are internal connections — do not use as tie points. Pin 9 may be used as tie point for components at heater potential.","Heater-cathode voltage: heater positive max 100V DC / 300V total DC and peak; heater negative max 900V DC / 6500V total DC and peak.","Maximum bulb temperature 220 degrees C (measured by infrared thermometer).","Average tube voltage drop: 16V at 400 mA, 25V at 800 mA (explicitly stated under 'Average Characteristics' in the GE Product Information sheet, page 2, 3-73). The 16V value at the rated 400 mA DC plate current is used as the canonical Vdrop.","Interelectrode capacitances (without external shield): cathode-to-plate-and-heater 22 pF, plate-to-cathode-and-heater 13.6 pF, heater-to-cathode 1.10 pF.","Heater current 0.45 +/- 0.03 A. Heater warm-up time approximately 11 seconds."],"references":["https://frank.yueksel.org/sheets/135/2/25DK3.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=25DK3","radiomuseum":"https://www.radiomuseum.org/tubes/tube_25dk3.html"},"raw_equivalents":[],"equivalents":[],"similar":[],"pins":[{"pin_number":"1","function":"Heater Insulation Coil","function_code":"ia","notes":null},{"pin_number":"2","function":"Plate","function_code":"a","notes":null},{"pin_number":"3","function":"No Connection","function_code":"nc","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":"Internal Connection — Do Not Use","function_code":"ic","notes":null},{"pin_number":"7","function":"Plate","function_code":"a","notes":null},{"pin_number":"8","function":"Internal Connection — Do Not Use","function_code":"ic","notes":null},{"pin_number":"9","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"TC","function":"Cathode (Top Cap)","function_code":"k","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"25","numeric_value":"25","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":"Damper Diode","tube_type_key":"rectifier","specs":[{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"9.0","numeric_value":"9","unit":"W","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"6500","numeric_value":"6500","unit":"V","param_group":"absolute_max"},{"key":"PIV","display_name":"Peak Inverse Voltage","value":"6500","numeric_value":"6500","unit":"V","param_group":"rectifier"},{"key":"Vdrop","display_name":"Voltage Drop (typical)","value":"16","numeric_value":"16","unit":"V","param_group":"rectifier"},{"key":"Idc_max","display_name":"Max DC Output Current (total, not per-anode)","value":"400","numeric_value":"400","unit":"mA","param_group":"rectifier"},{"key":"Ia_peak","display_name":"Peak Anode Current (surge)","value":"1200","numeric_value":"1200","unit":"mA","param_group":"rectifier"}]}],"synced_at":"2026-04-09T05:16:28.854Z"}