{"type_number":"Pen4VB","canonical_url":"https://tubeofile.com/tubes/Pen4VB","manufacturer":"Mullard","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"B7G","description":"Power output pentode with British 7-pin base, manufactured by Mullard. Notable for unusually high transconductance of 10 mA/V for its era (1930s). Designed for audio output service in AC radio receivers. Uses 4V indirectly heated cathode with 1.95A heater current.","is_directly_heated":false,"completeness":"medium","notes":["Unusually high transconductance (gm = 10 mA/V) for a 1930s power pentode.","Self-bias: 145 ohms cathode resistor needed for -5.8V bias at Va=250V, Vg2=100V.","Uses the old British 7-pin base (M7A) — not to be confused with the later B7G miniature base.","Brans Vademecum table Vc lists PenA4 and UCL82 as equivalents, though UCL82 is a triode-pentode compound tube and not a true equivalent.","Production era: primarily 1931-1937 per Radiomuseum documentation."],"references":["https://tdsl.duncanamps.com/show.php?des=Pen4VB","https://www.radiomuseum.org/tubes/?tube=Pen4VB"],"source_urls":{"r_type":null,"tdsl":"https://tdsl.duncanamps.com/show.php?des=Pen4VB","radiomuseum":"https://www.radiomuseum.org/tubes/tube_pen4vb.html"},"raw_equivalents":["PenA4"],"equivalents":[{"type_number":"PenA4","equivalence_type":"direct","notes":null}],"similar":[{"type_number":"AC2/Pen","reason":"Radiomuseum lists as normally replaceable — similar power pentode","has_detail_page":false},{"type_number":"N41","reason":"Radiomuseum lists as normally replaceable alternative","has_detail_page":false},{"type_number":"PT4","reason":"Radiomuseum lists as normally replaceable — similar Mullard power pentode","has_detail_page":false}],"pins":[{"pin_number":"1","function":"Anode","function_code":"a","notes":null},{"pin_number":"2","function":"Screen Grid (g2)","function_code":"g2","notes":null},{"pin_number":"3","function":"Control Grid (g1)","function_code":"g1","notes":null},{"pin_number":"4","function":"Cathode","function_code":"k","notes":null},{"pin_number":"5","function":"Heater","function_code":"h","notes":null},{"pin_number":"6","function":"Heater","function_code":"h","notes":null},{"pin_number":"7","function":"Suppressor Grid (g3)","function_code":"g3","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"4","numeric_value":"4","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"1.95","numeric_value":"1.95","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Power Pentode","tube_type_key":"power_pentode","specs":[{"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":"6","numeric_value":"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":"Vg","display_name":"Grid 1 Bias Voltage","value":"-5.8","numeric_value":"-5.8","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"30","numeric_value":"30","unit":"mA","param_group":"typical_operating"},{"key":"Vg2","display_name":"Screen Voltage","value":"100","numeric_value":"100","unit":"V","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"30000","numeric_value":"30000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"10","numeric_value":"10","unit":"mA/V","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"145","numeric_value":"145","unit":"Ω","param_group":"typical_operating"}]}],"synced_at":"2026-04-07T19:39:36.639Z"}