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SP18

Information - Help 
ID = 3792
       
Country:
Great Britain (UK)
Brand: Metropolitan-Vickers (Metro-Vick, Cosmos); GB
Tube type:  Triode, vacuum 
Identical to SP18
Similar Tubes
Normally replaceable-slightly different:
  SP18/B ; SP18/G ; SP18/R
First year 1925 Saga of the Vacuumtube, Tyne page 373

Base Europe 4-Pin (A, 4A, B4, since 1914)
Filament Vf 1.8 Volts / If 0.3 Ampere / Direct / Battery =
Description

This SP18 without dot or suffix (B, G, R) is definitely existing (see photo).

Shortpath is a Cosmos brand, see Keith R. Thrower, British Radio Valves, page 48. Probably an anglicised version of the WD11 from the USA.

According to Tyne (pp.373, 374) there are three variants:
- SP18/R (1925)
- SP18/G (1925)
- SP18/B (1926)
in the Benjamin Catalog all SP18 are tubular, although Tyne shows an SP18/G having a globe shape. Error?

The SP18/G or Green spot was selected as a general purpose hf and af tube for RC coupling. The SP18R or red spot was selected with a lower Ra for output operation and had a gm of 0.9 to 1.0 mA/V.

The advertised price in 1925 for red and green spots was 12/6 = 0.63GBP

Story of Cosmos valves see here

 
Text in other languages (may differ)
Tube prices 1 Tube prices (visible for members only)
Literature The Wireless World, London (WW, 79)   Advertisement by Metro-vick Dec 1925
 
sp18.jpg
SP18: KoBi
Konrad Birkner † 12.08.2014

 
b4sockel_3.png
SP18: KoBi
Konrad Birkner † 12.08.2014

 
sp18_spec.png
SP18: Banneitz, TB der drahtl. Teleph. 1927
Anonymous 15 Collector


Usage in Models 2= 1925

Quantity of Models at Radiomuseum.org with this tube (valve, valves, valvola, valvole, válvula, lampe):2


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