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AC_Pratt

Information - Hilfe 
ID = 79807
       
Land:
USA
Marke: Pratt, Harry Preston, Radio Tube Co.; Chicago IL
Entwickler: Pratt, Harry Preston, Radio Tube Co.; Chicago IL 
Typ:  TRIODE (Detail unsicher) 
  Ca. 1925 bis 1945, aber äusserst selten, weil weniger als 100 Röhren produziert wurden. ****
Identisch mit AC_Pratt

Sockel USA-UX-4-Stift-Sockel (2 dick), ab 1924 2 Obenanschlüsse.
Anwender Radio/TV-Empfang etc.
Heizung Indirekt / Spezifizierte Spannung UND Strom ~ =
Beschreibung US Patent No 1949395 relates to this tube. The patent was applied for by Harry Preston Pratt on November 23rd, 1928 and granted February 27th, 1934. It related to an alternating current heater type tube somewhat similar in outward appearance to the Kellogg and McCullough type 401 tubes available at the time. The difference in Pratt's tube was that it consisted of three separate bulbs. The outer bulb was a heat insulator, middle bulb held the grid and plate elements and the innermost bulb held the heater. All bulbs were completely sealed together. It is not known if these tubes were actually manufactured but because of their glass complexity, they would have been very expensive to make. It is quite probable that these did not advance beyond the experimental and patent stage. No tubes of this type have been located. As there has been no known type number allocated, for practical purposes the type AC_Pratt has been adopted. 
Literatur -- Original prospect or advert   US Patent No 1949395


Just Qvigstad
 

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