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ID = 78924
Brand: Philips; Eindhoven (tubes international!); Miniwatt
Developer: Philips; Eindhoven (tubes international!); Miniwatt 
Tube type:  SPECIAL TUBE, other or unknown 
  Ca. 1925 up to 1945 no serial production. For instance only development samples. *****
Identical to WN3-14
Successor Tubes 1940   DAH50  

Base SPECIAL TUBEBASE in general
Was used by Radio/TV-reception etc.
Filament Direct / Battery =

Philips early developmental sample of all-glass receiving tubes, later originating the B9G lock-in family. The sample has a rimmed spigot and nine pins, bented to lock the tube in the socket with a small rotation. Internal costruction visible from the clear glass envelope shows the presence of a diode mounted side-by-side to a four grid amplifier.

Jacob Roschy suggests this sample could be an early prototype of the DAH50. Actually it looks very similar, but for the apparent absence of the first beam-forming grid. Jacob also gives a conclusive explanation for the apparent involution from the all-glass prototype to the octal-based production type. In May 1940 the entire new line for manufacturing B9G tubes was hastily moved from Eindhoven to England just before German troops invaded Holland. Subsequently productions of the newly developed tubes in Holland had to be switched to types, as the octal-based ones, that could be handled by the old manufacturing lines.

The early development of B9G all-glass tubes can be read at the page:

The EF50, the Tube that helped to Win the War

Information source -- Collector info (Sammler)   

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