{"type_number":"ECH35","canonical_url":"https://tubeofile.com/tubes/ECH35","manufacturer":"Philips","tube_type_key":"triode_hexode","tube_type_display_name":"Triode-Hexode","base_name":"Octal","description":"Triode-hexode frequency converter for superheterodyne receivers. Octal base. Philips design from 1938. The triode section serves as local oscillator and the hexode section as mixer/frequency changer. Predecessor to the ECH81 Noval type.","is_directly_heated":false,"completeness":"high","notes":["Triode and hexode sections share a common cathode.","Screen grid supply through a potentiometer (R1, R2) from B+ for the hexode section.","The triode section is used as the local oscillator; the hexode section as frequency changer/mixer.","Hexode conversion conductance Sc = 650 uA/V at Va=250V, Vg2+g4=200V.","Limiting values: hexode Va_max = 550V, Vs_max = 300V; triode Va_max = 550V."],"references":["https://frank.pocnet.net/sheets/030/e/ECH35.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=ECH35","radiomuseum":"https://www.radiomuseum.org/tubes/tube_ech35.html"},"raw_equivalents":["ARTH2"],"equivalents":[],"similar":[{"type_number":"ECH4","reason":"Earlier side-contact base version — not pin-compatible","has_detail_page":true},{"type_number":"ECH81","reason":"Later Noval-base triode-heptode replacement — not pin-compatible","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Hexode Anode","function_code":"a2","notes":null},{"pin_number":"2","function":"Hexode Screen Grid (g2+g4)","function_code":"g2","notes":null},{"pin_number":"3","function":"Common Cathode","function_code":"k","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":"Triode Anode","function_code":"a1","notes":null},{"pin_number":"7","function":"Hexode Signal Grid (g1)","function_code":"g1","notes":null},{"pin_number":"8","function":"Triode Grid / Hexode Oscillator Grid (g3)","function_code":"g3","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":"0.2","numeric_value":"0.2","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode (Oscillator)","tube_type_key":"small_signal_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"550","numeric_value":"550","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"1.5","numeric_value":"1.5","unit":"W","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"0.1","numeric_value":"0.1","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"250","numeric_value":"250","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"3.3","numeric_value":"3.3","unit":"mA","param_group":"typical_operating"},{"key":null,"display_name":"Oscillator Voltage (Vosc)","value":"8","numeric_value":"8","unit":"Veff","param_group":null}]},{"section_number":2,"section_label":"Hexode (Mixer)","tube_type_key":"hexode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"550","numeric_value":"550","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"200","numeric_value":"200","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"1.2","numeric_value":"1.2","unit":"W","param_group":"absolute_max"},{"key":"Ps_max","display_name":"Screen Dissipation (max)","value":"0.6","numeric_value":"0.6","unit":"W","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"250","numeric_value":"250","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"100","numeric_value":"100","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-2","numeric_value":"-2","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"3","numeric_value":"3","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"1300000","numeric_value":"1300000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"0.65","numeric_value":"0.65","unit":"mA/V","param_group":"typical_operating"}]}],"synced_at":"2026-04-07T19:07:29.688Z"}