Amperex 6DJ8 tube construction

I agree the one with the extra plate may be a ruggedized tube.
Does the left tube have the same Amperex logo? This is a guess, maybe the tube on the right was made in a Mullard plant and branded Amperex Holland. That happened sometimes.

I think the circular plate is called a splatter shield. I don’t know what its function is.

Tubes from the Phillips factories (Amperex, Mullard, Siemens, La Radiotechnique, Valvo, etc.) made in one factory often carried the label of another Phillips factory. I have lots of examples of this.

The only way to be sure where and when a Phillips tube was made is to read the etched code. Sometimes part or all of the code is unreadable. I can see the delta etching on the tube on the left, which means it was made in the Heerlen Amperex factory. You would have to talk to someone a lot more familiar with tube construction than me to find out where the tube on the right was made.

Here is a link to the Phillips codes if anyone doesn’t have them:

https://frank.pocnet.net/other/Philips/PhilipsCodeListAB.pdf

The tubes we’re discussing and any we’re likely to come across would have the ’NEW’ CODE etchings.

The one on the left is Holland.

The one on the right looks to be Blackburn, England or Japanese.

If Blackburn it will have etched codes on the glass.

Japanese "Mullard" 6922 types usually have a slanted getter flashing that is higher/lower on opposite sides of the tube, but not always.

This "slant' was also common with some Eastern Euro 12 volt tubes from the 70's and maybe later on.

Anyway, both are desirable tubes if they test up to snuff.

DeKay

Everybody - thanks for the info. Solving a mystery is always fun.

With jeweler’s magnifying glasses, I wasn’t able find any codes - on any of the NIB/NOS Amperex 6DJ8’s in the yellow/green boxes. I looked everywhere - including the bottom and sides of the tubes. It was easy to find the the codes on the Heerlen-made tubes - of which I have several. The Heerlen-made tubes lasted several thousand hours in my preamp. Some are finally wearing out.

I’d like to find out more about the mid-circular plate. Unfortunately, no luck with a google search, re: vacuum tube splatter shield.

Maybe try Googling vacuum tube mica. Or mica types.