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ID = 14552
Great Britain (UK)
Brand: Common type Great Britain tube/semicond.
Tube type:  Triode, vacuum   Universal 
  <1925 very rare. ***
Identical to NR15A = CV1152 = 7404A
Predecessor Tubes NR15   CV1151  

Base Europe 4-Pin B4 (Eu A, E, 4A) 1914 (Codex=Eo)
Was used by Military and/or Government
Filament Vf 3.8 Volts / If 0.1 Ampere / Direct / Battery =

Improved NR15 with anode impedance reduced from 20 to 6 kohms and anode current raised from 1.6 to 4.5 mA. British Admiralty Pattern 7404A

Information source Taschenbuch zum Röhren-Codex 1948/49   
-- Original-techn. papers.   

pm3_1.png NR15A: Manufacturer's Literature
Emilio Ciardiello

Just Qvigstad
NR15A: Manufacturer's Literature
Emilio Ciardiello

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Forum contributions about this tube
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NR15A (NR15A)
Júlio Branco

The NR15A is a British Navy triode receiving valve. Introduced in 1924 it was the first naval valve to have an oxide coated filament. This valve looks to have been made by the Azide process.

The photograph is essentially an MOV type L410 manufactured during the mid to late 1930s. Although the Azide process was essentially obsolete by this time it was used occasionally, and British Navy specifications may have remained unchanged for years after the technology altered.

This example dates from 1936 by which time it was known as the 'Lord Louis' valve in honour of the improvements Lord Louis Mountbatten is reported to have suggested.
The balloon envelope is 40 mm in diameter and, excluding the B4 base pins, is 85 mm tall.

Made &Patentead in England


Best Regardes

Júlio Branco


Changed it from "other language" to English.

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