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THE GREAT MULLARD MAGIC BLOG — sylvania

ALL ABOUT SYLVANIA SARONG CATHODE COATINGS

Posted by STEVE M on

ALL ABOUT SYLVANIA SARONG 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/);...

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THE JAN CODE - WHAT DO THE ALPHANUMERIC AND ALPHA CODES MEAN?

Posted by STEVE M on

THE JAN CODE - WHAT DO THE ALPHANUMERIC AND ALPHA CODES MEAN?

Hi peeps, well, in response to another valve related query, this time about 'JAN codes', I thought I would pen a little information nuggett here today. I shall be doing a further more detailed blog entry on military coding history and types soon but for now here's a quick info - bite. The JAN code is of course the US Military Joint Army Navy coding introduced in 1942 in which the code for a particular valve type comprises of an alphanumeric code, for example VT-114 and additionally a three digit alpha code. I will deal with the former in more...

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A PRIMER ON VALVE BASES - WHEN WERE CERTAIN TYPES INTRODUCED?

Posted by STEVE MYCIUNKA on

A PRIMER ON VALVE BASES - WHEN WERE CERTAIN TYPES INTRODUCED?

Mama Mia!  An e-mail from Vigata in Sicily enquiring about when certain valve bases were introduced.   I know a valve dealer from Sicily you know, he's from Messina and ever such a nice chap but I digress........ There exists a whole raft of valve bases, however, I shall deal with only the most commonly seen bases and their dates of introduction in the following table:- Year of Introduction Valve Base Type Descriptive notes 1916 B4 Introduced by French valve manufacturer Duclos-Fivre 1927 B4 + side screw Introduced for indirectly heated cathodes 1928 B4 + top cap VHF/ UHF anode top...

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