EL84 thermionic valve anatomy.

Good day thermophiles.

Recently this valve was starting to sound cold and transistor-like so I decided I would open it and repair it myself. I took a few photos as a guide for others who would like to service and tweak their own valves.

I will update the captions with more detail later, but for now I will only provide a title for each photo.


You will need a special valve opening tool. Bizarrely some people use it to open acorns too.


Pristine EL84 that sounds like a solid state device lately.


Getter material in the top of the valve glass envelope. I suspect it is barium (I will confirm later). It is used to absorb oxygen inside the vacuum.




Glass removed.


Top washer with getter.


Anode removed.


Anode.


Suppressor grid.


Screen grid bottom. Suppressor grid top.


Control grid bottom. Screen grid top.


Cathode.


Heaters.


Base.


All the parts in an order similar to that which they would be in the valve.


Soon I will glue (or duct tape) all the pieces back together and try the valve in my favourite mono amplifier.