{"type_number":"12AZ7","canonical_url":"https://tubeofile.com/tubes/12AZ7","manufacturer":"Tung-Sol","tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Noval","description":"Medium-mu twin triode, miniature type. Two independent medium-mu indirectly heated cathode type triodes in a 9-pin miniature construction. Adaptable to application either as an AF amplifier or as combined oscillator and mixer.","is_directly_heated":false,"completeness":"high","notes":["Heater can be wired in series (12.6V, 225mA) or parallel (6.3V, 450mA). For 12.6V operation, apply voltage between pins 4 and 5. For 6.3V operation, connect pins 4 and 5 together and apply voltage between that junction and pin 9.","Internal shield connected between pin 3 (section 2 cathode) and pin 5 (heater). Capacitance specs are measured with this shield grounded.","Two sets of typical operating conditions are published: a high-current point at Va=250V / Ia=10mA (gm=5.5 mA/V, ra=10.9 kΩ) and a low-current point at Va=100V / Ia=3.7mA (gm=4.0 mA/V, ra=15 kΩ).","Max grid-circuit resistance differs between cathode-bias (1.0 MΩ) and fixed-bias (0.25 MΩ) operation.","Electrically identical to the 12AT7 (same mu, gm, ra, max ratings) but with higher heater current (225mA vs 150mA series) and higher max heater-cathode voltage (200V vs 90V). Designed for use in series-string transformerless TV receivers and test instruments with elevated heater-cathode voltage."],"references":["https://frank.pocnet.net/sheets/127/1/12AZ7.pdf"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=12AZ7","radiomuseum":"https://www.radiomuseum.org/tubes/tube_12az7.html"},"raw_equivalents":["12AZ7A"],"equivalents":[],"similar":[{"type_number":"12AT7","reason":"Same 9A pinout and similar mu (~60), but different heater current (150mA vs 225mA series). Not interchangeable in series-string heater circuits. Sams Handbook lists as substitute for parallel-filament circuits only.","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Plate (Section 2)","function_code":"a2","notes":null},{"pin_number":"2","function":"Grid (Section 2)","function_code":"g1_2","notes":null},{"pin_number":"3","function":"Cathode (Section 2)","function_code":"k2","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":"Plate (Section 1)","function_code":"a1","notes":null},{"pin_number":"7","function":"Grid (Section 1)","function_code":"g1_1","notes":null},{"pin_number":"8","function":"Cathode (Section 1)","function_code":"k1","notes":null},{"pin_number":"9","function":"Heater Center-Tap","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"12.6 / 6.3","numeric_value":"12.6","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.225 / 0.45","numeric_value":"0.225","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":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"2.5","numeric_value":"2.5","unit":"W","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"200","numeric_value":"200","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"1.0","numeric_value":"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":"Vg","display_name":"Grid 1 Bias Voltage","value":"-12","numeric_value":"-12","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"10","numeric_value":"10","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"10900","numeric_value":"10900","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"5.5","numeric_value":"5.5","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"60","numeric_value":"60","unit":"—","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"200","numeric_value":"200","unit":"Ω","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"1.9","numeric_value":"1.9","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"2.8","numeric_value":"2.8","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"1.4","numeric_value":"1.4","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:04:30.626Z"}