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ID = 49547
United States of America (USA)
Brand: Marconi Wireless Telegraph Co. of America
Developer: Moorhead Laboratories (Pacific); San Francisco 
Tube type:  Triode, vacuum   Universal 
  <1925 rare.
Identical to VT-Class-II = TypeA = A_Moorhead
First year 1919 Saga of the Vacuum Tube, Tyne page 172/173

Base UV-Base (4 Pins+Bayonet, USA 1914 WE)
Was used by Radio/TV-reception etc.
Filament Vf 4 Volts / If 0.7 Ampere / Direct / Battery =
Description "Hard" tube, 60 - 90 volts at the anode. The VT-Class II (a Type A tube) is a "hard" tube for 60-90 volts and similar to the VT-Class I (a Type B tube), which is a "soft" tube for detector application with 18 - 40 volts at the anode. There is a series of similar tubes: Type A, Type B, Type C, Type D, Type E and Type F (see Tyne page 172 for more information) and spherical Type G with British standard four-pin base.
The tubes advertised and sold by the American Marconi Company in 1919 and early 1920 as the Marconi VT were Type A and Type B tubes. A life of 1500 hours was claimed for these tubes. The first consignment of tubes (about 25,000) delivered to Marconi bore no Marconi or de Forest markings. They were stamped on the glass bulb with the legend "Moorhead Audion - San Francisco". The class is rubber-stamped on the base. About 800 of these tubes have been sold. The remainder got the words "Patented Nov. 7, 1905. Sold for amateur and experimental use". According to Tyne page 173 this was stamped at the bulb before being sold. Subsequently both the Marconi and de Forest patent numbers and the restrictive legend were steel-stamped at the brass base. 
Dimensions (WHD)
incl. pins / tip
44 x 102 x 35 mm / 1.73 x 4.02 x 1.38 inch
Information source Saga of the Vacuum Tube, Tyne   p.173
  VT-Class-II: own collection
Peter den Boer
Geri Meier

VT-Class-II: own collection
Peter den Boer


from Just Qvigstad

Usage in Models 14= 1919 ; 39= 1920 ; 2= 1921? ; 7= 1921 ; 1= 1922? ; 1= 1922

Quantity of Models at with this tube (valve, valves, valvola, valvole, válvula, lampe):64

Documents about this component
  Reciever with Marconi VT tubes 3103 KB

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