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Round Radio Valve Type N, by Ediswan, London, c. 1915

Inventory Number: 39244

39244-2t 39244-1t

Date: c. 1915

Maker Details: Attributed to Ediswan.

Inscription: "MARCONI'S W. T. CO. LTD. / PAT. APPN. NO 28413-13. / 2V - PIF / N706" printed on exterior surface of bulb.

Size: 180 mm in overall height (including tip and base)

Materials: Glass, steel, asbestos, platinum-iridium, assorted metals.

Other Given Number(s): Christie's 201.


Round Triode Radio Valve Type N, with Edison screw cap base and asbestos-filled tip for heating. The Type N Marconi Triode dates to 1914-15 and PIF indicates a single strand Platinum Iridium filament. The Type N valve had a thick mesh gird and, as per this example, was usually fitted with an Edison screw cap but sometimes featured a bayonet cap. The Type N was a receiver valve and was used as a High Frequency (HF) amplifier, covering wavelengths in the range 60-500 kHz. The Type N replaced the Type C valve, with which it shared a similar construction, in Naval use in 1916.

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