{"type_number":"EL5","canonical_url":"https://tubeofile.com/tubes/EL5","manufacturer":"Philips","tube_type_key":"power_pentode","tube_type_display_name":"Power Pentode","base_name":"P8A","description":"Output pentode with 18 W anode dissipation; indirectly heated. Introduced by Philips in 1936 as a high-power successor to the 9 W pentodes, offering double the output with the same physical envelope size. P8A side-contact base with top-cap anode connection.","is_directly_heated":false,"completeness":"medium","notes":["Heater power is only 8.4 W for 18 W anode dissipation — exceptionally favorable ratio for the era.","Transconductance (7 mA/V) is notably higher than contemporary 9 W pentodes like the EL2 (2.8 mA/V), requiring only 0.5 Veff input for 50 mW output sensitivity.","Anode and screen voltage are both 250 V — no separate high-voltage supply needed, simplifying power supply design.","Heater current of 1.35 A (later reduced in successor EL3N to 0.9 A) makes this tube unsuitable for series-heater strings.","Anode connection is via top cap. The P8A side-contact base carries heater, cathode, grids, and metallization.","For 5 W output at slightly above 5% THD, or 7.7 W at 10% THD in Class A single-ended operation."],"references":["https://frank.pocnet.net/sheets/145/e/EL5.pdf"],"source_urls":{"r_type":null,"tdsl":null,"radiomuseum":"https://www.radiomuseum.org/tubes/tube_el5.html"},"raw_equivalents":["6E7","3RKP6","TEL5","VEL5"],"equivalents":[],"similar":[{"type_number":"AL5","reason":"4 V heater version (AL5 = 4 V, EL5 = 6.3 V) — not interchangeable without heater modification","has_detail_page":true},{"type_number":"EL12","reason":"Successor design with Y8A base — different base, different pinout","has_detail_page":true},{"type_number":"EL35","reason":"Electrically identical but Octal (IO) base instead of P8A side-contact — not pin-compatible","has_detail_page":true},{"type_number":"EL5G","reason":"Glass envelope variant with different bulb shape — check base compatibility","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Control Grid","function_code":"g1","notes":null},{"pin_number":"2","function":"Cathode","function_code":"k","notes":null},{"pin_number":"3","function":"Heater","function_code":"h","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Screen Grid","function_code":"g2","notes":null},{"pin_number":"6","function":"Metallization (external shield)","function_code":"ia","notes":null},{"pin_number":"7","function":"Suppressor Grid (internally connected to cathode)","function_code":"g3","notes":null},{"pin_number":"8","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"TC","function":"Anode (top cap)","function_code":"a","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":"1.3","numeric_value":"1.3","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Pentode","tube_type_key":"power_pentode","specs":[{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"18","numeric_value":"18","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":"250","numeric_value":"250","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-16","numeric_value":"-16","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"72","numeric_value":"72","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"7.5","numeric_value":"7.5","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"33000","numeric_value":"33000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"7","numeric_value":"7","unit":"mA/V","param_group":"typical_operating"},{"key":"Rk","display_name":"Cathode Resistor (self-bias)","value":"200","numeric_value":"200","unit":"Ω","param_group":"typical_operating"},{"key":"Pout","display_name":"Output Power","value":"7.7","numeric_value":"7.7","unit":"W","param_group":"output"},{"key":"rl","display_name":"Load Impedance","value":"3500","numeric_value":"3500","unit":"Ω","param_group":"output"}]}],"synced_at":"2026-04-07T12:45:24.638Z"}