Antique radios, Old Time Radios
AC_Pratt
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Country:
United States of America (USA)
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| Identical to |
AC_Pratt
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| Base |
UX-Base (4 Pins (2 thick, USA 1924, UX)
2 Top contacts.
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| Was used by |
Radio/TV-reception etc. |
| Filament |
Indirect / Specified voltage AND current AC/DC |
| Description |
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.
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| Information source |
-- Original prospect or advert US Patent No 1949395
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