Tube ID and info needed - burn marks?

[bberkom]

I have this quad of 6GW8/ECL86 tubes that I pulled from a Fisher Philharmonic console amp. Both the triode and pentode sections of all four tubes test very strong on my Sencore Mighty Mite tube tester, but they exhibit some burn marks on the inside of the glass, as you can see in the photos. My first question is, are these tubes really still good, even with the burn marks? I don't have a working amp in which to test them. I won't be using them, so I'd like to sell them to someone who can use them. I don't want to sell bum tubes if I can help it. I'll probably end up posting them for cheap on BT.

Second question would be that of the manufacturer. The construction most closely resembles the RCA version of this tube when I compare to photos, and these were the original Fisher-branded tubes. The only other markings I can make out are W. Germany and then the code WS2 on all four tubes. Additionally, two of the tubes have code D0K, and the other two have D0I and D0J. Any help is appreciated.

 

[cademan]

They're not burn marks but more like stains. Usually that's a trait of
Mullard tubes.

 

[CZ4A]

D= Valvo, Hamburg per the Philips factory valve code list. WS confirms the tube type as ECL86/6GW8.

 

[bberkom]

They're not burn marks but more like stains. Usually that's a trait of
Mullard tubes.

That’s good news if it’s normal staining, and I see similar stains now when I look up similar Mullard tubes.

D= Valvo, Hamburg per the Philips factory valve code list. WS confirms the tube type as ECL86/6GW8.

I thought that might be the case, but they don’t look like any other Valvo tubes of this type when I search. And if they aren’t Mullard, should I be worried about the staining? Or could that happen with other makes and not indicate an issue? Again, they tested super strong with no leakage or shorts.

 

[primosounds]

Most of that type is made by Mullard or Phillips, no matter the brand.

 

[gadget73]

The brown stains are a thing that Mullard types do. No clue why, but it doesn't seem to indicate anything other than they aren't NOS.

I don't suppose you still have the amp do you? That should be a nice sounding piece of kit.

 

[BillWojo]

I purchased some used but tested very strong Russian 6P14P-EV off of Ebay for 5 bucks each. I managed to get 3 closely matched sets out of the 10 tubes. Anyway, all of these tubes have the "Smoky Mullard" stains in the glass. So it seems that Mullard isn't the only one.

BillWojo

 

[bberkom]

The brown stains are a thing that Mullard types do. No clue why, but it doesn't seem to indicate anything other than they aren't NOS.

I don't suppose you still have the amp do you? That should be a nice sounding piece of kit.

I do still have it, but it’s in pretty rough shape, and I am trying to clear out my projects pile that I’m not able to get to and don’t have room for.

 

[gadget73]

Understand. List it, someone will probably want it as a project, even if just for the transformers. I've got a backlog myself so I understand the issue.