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al5 4688 Philips black mesh tube pair power tubes matched audio pentode strong

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Original price was: $615.12.Current price is: $369.07.

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Country/Region of Manufacture : Netherlands
Model : al5 4688
Custom Bundle : No
Brand : Philips
Type : Power Tubes
MPN : al5 4688
Modified Item : No

2 tubes AL5 Philips Miniwatt gold ring bottom & black coated glass, big fat shape black mesh plate round copper rods power pentode for last stage audio tubes extra rare tested on tube tester Funke W19S = 56mA & 59mA (reference good at 30mA) with 200 Volt on anode old production year 1936 tube type: power output pentode for last stage audio AL5 = WE42 = A70E = TAL5 = NLP62 = RAL5 = VAL5 = 4E2 = 4A27_Ultron first informations Apr.1936 : Philips Bulletin D35 sub the models: F443N L495D Evolution in year 1938: EL6 EL12 EL12/375 Socket Europe side contact P8A Filament Heater Vf 4 Volt / If 2 Ampere / Indirect / Specified voltage AC/DC history & development around AL5 power tube By demand of more output power new output tubes appeared in 1936 with plate dissipation increased from 9 to 18 watts. In Europe it were the pentodes AL5 (4Vf) and EL5 (6.3Vf), in the USA it was the worlds first and most famous beam- power-tetrode, the 6L6. The AL5 was introduced by Philips in April 1936 in their monthly bulletin #35, designed in the then contemporary technology as normal pentode with round cathode More than one year later, Telefunken presented its own version of the AL5 in July / August 1937, which was strongly oriented at the beam power tetrode 6L6, developed by RCA, with beam confining electrode and aligned control- and screen grid windings, thus the Telefunken AL5 became Europe’s first beam power tetrode box 209

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