{"type_number":"1H4","canonical_url":"https://tubeofile.com/tubes/1H4","manufacturer":"Tung-Sol","tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Octal","description":"General-purpose directly heated filament triode designed for battery-operated receivers. Octal base (G-5Z basing). Electrically identical to the type 30 except for interelectrode capacitances and base type. Coated filament rated at 2.0V DC / 0.06A.","is_directly_heated":true,"completeness":"medium","notes":["Tung-Sol datasheet states: 'With the exception of capacitances its ratings and characteristics are identical with those of the 30.'","Filament is DC only (battery supply). The 2.0V/0.06A filament is designed for single dry-cell operation.","With maximum signal, average DC plate current should not exceed 2.0 mA in Class A1 amplifier service.","Grid return is to negative end of filament (approximate). Datasheet notes this as approximate for all operating conditions.","Detector operation: grid-leak mode with 1-5 MΩ grid leak and 250 pF grid condenser at Va=45V; biased mode at Va=90-180V with grid return to negative filament.","1H4G and 1H4GT are glass envelope variants; same electrical tube."],"references":["https://frank.pocnet.net/sheets/127/1/1H4G.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=1H4G","radiomuseum":"https://www.radiomuseum.org/tubes/tube_1h4g.html"},"raw_equivalents":["1H4G","1H4GT"],"equivalents":[],"similar":[{"type_number":"30","reason":"Electrically identical (same mu, ra, gm) but UX4 base — 1H4G is the Octal-base replacement","has_detail_page":true}],"pins":[{"pin_number":"1","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"2","function":"Filament (+)","function_code":"h","notes":null},{"pin_number":"3","function":"Plate","function_code":"a","notes":null},{"pin_number":"4","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"5","function":"Grid","function_code":"g1","notes":null},{"pin_number":"6","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"7","function":"Filament (-)","function_code":"h","notes":null},{"pin_number":"8","function":"No Connection","function_code":"nc","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"2.0","numeric_value":"2","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.06","numeric_value":"0.06","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode","tube_type_key":"small_signal_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"180","numeric_value":"180","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"2","numeric_value":"2","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"135","numeric_value":"135","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-9","numeric_value":"-9","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"3.0","numeric_value":"3","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"10300","numeric_value":"10300","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"0.9","numeric_value":"0.9","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"9.3","numeric_value":"9.3","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"5.0","numeric_value":"5","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"3.6","numeric_value":"3.6","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"5.0","numeric_value":"5","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:07:07.586Z"}