How worn out should NOS tubes look?

[Schmitz77]

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to day every body knows abut original telefunken valves and zaerix story . you can see my el90s in pics.these tubes are magic.

But do you know even the TFK diamond bottom has been faked by laser? Very hard to see just from pics but clearly identified as fake TFK tubes.

 

[hooman]

Yes, everything happens with technology. But I took an honest picture from 5 valves .nos el90 are not expensive .
The curves of the tubes and the correct bias point are necessary for a good sound, but the lamps differ in sound and this is my personal experience

 

[Schmitz77]

The curves of the tubes and the correct bias point are necessary for a good sound, but the lamps differ in sound and this is my personal experience[/QUOTE]
This is because we hear materials used and the manufacturing process in combination with operating points. Not more and not less.

 

[Kay Pirinha]

here are a couple of real NOS, the plastic cellophane wrapper still intact,
i guess they don't do this anymore today....
i am keeping this in my collection of genuine NOS tubes....

Yes, Tony, especially there's no need for this PCF86 to be pulled out of it's wrapping and box, as I never have seen any reasonable usage for this strange common cathode triode-pentode conbination.

Btw, I'm not able to decipher the characters written on the bigger box...

Best regards!

 

[Kay Pirinha]

But do you know even the TFK diamond bottom has been faked by laser? Very hard to see just from pics but clearly identified as fake TFK tubes.

I'm not able to imagine how one would create this elevated rhomb to the bottom of a valve, i.e. by adding glass, by means of a laser?


Best regards!

 

[TonyTecson]

Yes, Tony, especially there's no need for this PCF86 to be pulled out of it's wrapping and box, as I never have seen any reasonable usage for this strange common cathode triode-pentode conbination.

Btw, I'm not able to decipher the characters written on the bigger box...

Best regards!

a radford circuit can use that tube...

the bigger box contained 10EW7,....

 

[Schmitz77]

I'm not able to imagine how one would create this elevated rhomb to the bottom of a valve, i.e. by adding glass, by means of a laser?


Best regards!

The laser takes material away but a rhomb can be cut into the bottom. And under microscope very small cracks in glass are visible different to original tubes.

 

[w5jag]

... My test system is comcludent and works well. ...... which gives excellent results, at least to me. ...... So this all works with quite good results but it has taken a while (to be exact, nearly 40 years) to have achieved the knowledge and experience. .....

There is a colloquial (sp?) expression in this country called "I know it when I see it" most famously used in the late Supreme Court Justice Potter Stewart's reference to hard core pornography. No doubt he did know it when he saw it, but it was an impossible standard of reference for people practicing in the field who had to make the determination.

I sort of think this is what Schmitz77 is saying - he knows it when he sees it.

I actually feel the same way - I've seen tens of thousands and I think I have a pretty good instinct for unused versus used on most tubes, but I doubt I could ever articulate a clear cut methodology. I just know it when I see it ....

But I have been wrong in the past, and probably will be again in the future. There are some tubes, some transmitting tubes in particular, or graphite coated glass, or other characteristics, where it is just impossible to say with any degree of accuracy.

I think it's much ado about nothing, anyway. If it doesn't work the way you want in circuit, provenance doesn't fix that.

Win W5JAG