{"type_number":"6DM4","canonical_url":"https://tubeofile.com/tubes/6DM4","manufacturer":"Tung-Sol","tube_type_key":"diode","tube_type_display_name":"Diode","base_name":"Octal","description":"Half-wave vacuum rectifier with indirectly-heated unipotential cathode, employing a T-9 envelope. Designed specifically for use as a damper diode in horizontal-deflection circuits of black-and-white television receivers. Tung-Sol design, dated January 1962.","is_directly_heated":false,"completeness":"high","notes":["Short intermediate-shell 5-pin Octal base with external barriers (B5-82 or B5-85 / B6-60), basing diagram JEDEC 4CG. Outline drawing JEDEC 9-44.","Except for heater characteristics and heater warm-up time, the 6DM4 is identical to the 12DM4 and 17DM4.","PIV rating of 5000V applies for a 525-line, 30-frame TV system where the duty cycle of the voltage pulse does not exceed 15% of one horizontal scanning cycle (10 µs).","Maximum peak heater-cathode voltage: 5000V (heater negative, DC component max 900V) / 300V (heater positive, DC component max 100V).","Socket terminals 1, 2, 4, and 6 should not be used.","Voltage drop of 35V at 400mA is higher than many Compactron/Novar dampers (e.g. 6BJ3 at 21V, 6CJ3 at 25V), reflecting the older design."],"references":["https://frank.pocnet.net/sheets/127/6/6DM4.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=6DM4","radiomuseum":"https://www.radiomuseum.org/tubes/tube_6dm4.html"},"raw_equivalents":["6DM4A"],"equivalents":[],"similar":[{"type_number":"6AS4","reason":"Radiomuseum lists as normally replaceable-slightly different — same base, verify pin-for-pin compatibility","has_detail_page":false},{"type_number":"6AX4","reason":"Same Octal base and active pin functions (JEDEC 4CG family) but lower PIV (4400V) and different ratings","has_detail_page":true},{"type_number":"6DA4","reason":"Same Octal base and JEDEC 4CG pinout but lower ratings (PIV 4400V vs 5000V, Ia 155mA vs 175mA, Pa 5.5W vs 6.5W)","has_detail_page":true},{"type_number":"6DE4","reason":"Same Octal base and pinout, similar damper diode — verify ratings before substitution","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Internal Connection","function_code":"ic","notes":null},{"pin_number":"2","function":"Internal Connection","function_code":"ic","notes":null},{"pin_number":"3","function":"Cathode","function_code":"k","notes":null},{"pin_number":"5","function":"Plate","function_code":"a","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","notes":null},{"pin_number":"8","function":"Heater","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"6.3","numeric_value":"6.3","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"1.2","numeric_value":"1.2","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Damper Diode","tube_type_key":"diode","specs":[{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"6.5","numeric_value":"6.5","unit":"W","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"5000","numeric_value":"5000","unit":"V","param_group":"absolute_max"},{"key":"PIV","display_name":"Peak Inverse Voltage","value":"5000","numeric_value":"5000","unit":"V","param_group":"rectifier"},{"key":"Vdrop","display_name":"Voltage Drop (typical)","value":"35","numeric_value":"35","unit":"V","param_group":"rectifier"},{"key":"Idc_max","display_name":"Max DC Output Current (total, not per-anode)","value":"175","numeric_value":"175","unit":"mA","param_group":"rectifier"},{"key":"Ia_peak","display_name":"Peak Anode Current (surge)","value":"1100","numeric_value":"1100","unit":"mA","param_group":"rectifier"}]}],"synced_at":"2026-04-08T07:52:38.110Z"}