THE GREAT MULLARD MAGIC BLOG — cathode coatings

In 1959, Sylvania made much of their new technology cathode coating process which they termed 'Sarong'.    The coating was characterised by an enhanced surface smoothness which to a certain extent was a 'Sword of Damocles' On the one hand, the smoothness of coating would lessen the effect of localised 'hot spots' - not much of a problem with the small signal valves shown in contemporary literature.  Conversely, there would be a reduction in surface area that could lower emission and cathode life.   As you can see, you pays your money and makes your choice. A sarong or sarung (/səˈrɒŋ/);...