Amperex 6DJ8 tube construction

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.

steakster, I found a couple of references to splatter shields, first from Joe’s Tube Lore:

"The next structure up is the unique one it’s a horizontal, circular, metal disc supported by two metal bars. I’ve seen & heard this referred to as a shield or a splatter shield. Which name is correct & what is the purpose of this structure? I don’t know, but most all early 6DJ8 family tubes have it."

https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html#6DJ8

and this out-of-stock tube on Tubemonger’s site:

"LORENZ Stuttgart PCC88 7DJ8 SINGLE TUBES Gray Shield 1960s MINT NOS OEM NO LABEL - Getter Ring Fused with Splatter Shield Construction - Made in Germany"

https://www.tubemonger.com/LORENZ_Stuttgart_PCC88_7DJ8_Gray_Shield_Germany_II_p/1054b.htm

I think you’ll have to call a tube dealer to get an answer. Let us know if you get one.

Joe's Tube Lore refers to the A frame type but that tube by construction does not have the ususal type of shield as earlier tubes (like the one on left picture).

What is common in Dutch made tubes, including Mullard, Amperex USA, French, Belgian, Indian and so on, and German tubes like Siemens and Halske, Telefunken (same tooling and construction for early Teslas also) is the ridged shield - a plate with two ridges 180 deg apart.
Sylvania, Tungsram (Hungary) had a plate shield with no ridges.
All for ecc88 family of tubes.