Zaerix ECC83 (12AX7)

[DF96]

B0J1 / B0F3 date codes.Any guess where they were made in and when?

No need for guessing about where, unless the code is incorrect.

Also , think otherwise, Philips with Δ on glass always meant it was made in Heerlen only.

The delta means Heerlen, not Heerlen only.

I suspect that 2-seam glass is actually 4-seam glass but with two seams very faint, not two seams missing.

 

[Panicos K]

No need for guessing about where, unless the code is incorrect.


The delta means Heerlen, not Heerlen only.

I suspect that 2-seam glass is actually 4-seam glass but with two seams very faint, not two seams missing.

The codes on the Zaerix are correct.
I emphasized "Heerlen only" because there is no way to have the Δ and be made anywhere else.
And,no faint seams, genuine Mullards/UK always had only 2 seams.

 

[DF96]

I emphasized "Heerlen only" because there is no way to have the Δ and be made anywhere else.

But surely that is true for any correct code: it shows where that particular item was made, so it could not have been made anywhere else.

 

[Panicos K]

But surely that is true for any correct code: it shows where that particular item was made, so it could not have been made anywhere else.

Agreed.This,together with some other points were used to clearly show the origin of the tubes.The seams for example, when you see a Philips with 2 seams, it will surely have the B--- or B-- date code too and either I61 or I63 marks.This means that it was made by Mullard for Philips.The same you can find Mullard with 4 seams and Philips date codes.They used to do this very often, to help each other catch-up with demand.Mullard were making tubes for Philips,Tungsram,Siemens,Philips were making tubes for Mullard and others and so on.Not very complex actually if you know the standard markings,codes and date coding system of each one of them.
I have discovered a few weeks ago, that another Zaerix 12ax7 I have, it was actually made by Philips plant in Japan.Same tubes,I have seen as RCA too!!!!