Summary
Sharp cut-off pentode designed for use as an audio amplifier, RF or IF amplifier, autodyne frequency changer or detector in radio receivers.
2.5 volt indirectly heated cathode.
National Union was formed in 1929 by the merger of four smaller American manufacturers: Sonatron, Magnatron, Marathon and Televocal; they remained in business until the early 1950s.
Manufacturer: National Union Radio Corp., Orange, NJ, USA
Physical Description
Shouldered glass bulb with top cap mounted on a 6 pin American style base. Base has been reglued.
More Information
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Collection Names
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Collecting Areas
Engineering, Information & Communication, Public Life & Institutions
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Acquisition Information
Unknown Acquisition Method from Unknown Source, 1981
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Manufacturer
National Union, Orange, New Jersey, United States of America, circa 1932
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Inscriptions
Bulb: None Paper label on base: NU-57 Base: NATIONAL/UNION/NU-57
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Classification
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Category
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Discipline
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Type of item
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Overall Dimensions
125 mm (Length), 38 mm (Outside Diameter)
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Keywords