Thursday, April 9, 2015

Tube of the Month : The E55L (revisited)

Hi!

Since I used the E55L in a headphone amp recently, this is a good opportunity to have a closer look at the tube again. The first tube of the month post about the E55L did not show any photos of the internals, so it is time to revisit it.




Technical details of the tube have already been covered in the first post. So this one will just show photos.

Philips Miniwatt E55L:




Amperex:




Another Amperex:




Telefunken:




Mullard:




For closer inspection of the internals I picked the Amperex with green letters. A close up before it is getting destroyed:




The glass removed:





Peeking into the side opening of the pate already gives an idea of the fine structures of the grids:




The top with the getter ring:




Side view:




A close up showing the pins going through the glass:




The plate removed from the system:





This leaves the remaining assembly exposed, cathode, control and screen grids and beam forming plate:




A close up to the rod which holds the screen grid:





The heater wire inside the cathode:




Heater wire partially pulled out:




Close up:





The heater:




Cathode and control grid:




The control grid wires are extremely fine and barely visible:




A human hair in comparison:




A close up shows what a marvellous piece of engineering the control grid structure is:




Cathode and control grid separated:




More views of the grid:







And lastly a few photos of glowing EL55s:









Best regards

Thomas



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