Wednesday, February 18, 2015

Round Plates

This is a circa 1990 Alessa Vaic copy of a Marconi R-type and it has that beautiful round plate structure we have grown to love. 

Unfortunately the tube has no emission and the real purpose for this post is behind the tube which is a set of iron for another round plate tube that does the R-type X 4... the 304TL.

The bigger ones are the SE outputs that can take 200ma of plate current while putting out 40 watts at 50hz.  They have bandwidth (-1dB) from 7hz to 49Khz and can do all of this due to the offset winding that runs the 12.5A filament current through the outputs in the opposite direction as the B+.  This brings the other two chokes into play which are the 20mhy 12.5A filament chokes that keeps the offset winding from loading down the tube.

The set of 4 weighs in at 46 pounds of copper and amorphous and boy am I glad the topic of silver never came up.


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