Summary
Triode, made by Mullard, England, introduced in late 1920s. It was used in radios as an output amplifier.
Valves with the PM prefix were produced from 1923 after Mullard formed a 'Philips-Mullard' joint venture with the Dutch electronics manufacturer Philips, in order to meet the technical demands of the newly formed BBC. Philips later acquired a controlling interest in Mullard in 1927.
A paper label on the base includes the warning in red that there is no glow from this filament. Typically a user would expect a working valve to have a glow. Someone who did not heed thsi warning might be tempted to raise the filament voltage to obtain a glow; this would burn out the filament.
It had a 4.0 Volt directly heated cathode and was used as class A power output amplifier.
Physical Description
Four pin American style base.
More Information
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Collection Names
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Collecting Areas
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Acquisition Information
Donation from J. Kleesman, 17 Feb 1972
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Manufacturer
The Mullard Radio Valve Co. Ltd, London, England, Great Britain, 1926-1930
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Inscriptions
Bulb: Registered Trademark Radio Mullard Valves MULLARD PM254
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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
115 mm (Length), 45 mm (Outside Diameter)
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References
[Book] Babani, Bernard B. 1958. International Radio Tube Encyclopaedia., 1958, 130 Pages
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Keywords