Recognizing wiped out ECC's 81,82,83

[Valvomaniac]

Hi,

I always find a lot of used ECC8? tubes with the numbers & labels wiped out. Some times - when parts of the label is showing- I can tell its a Mullard or Telefunken etc.

The Question is: How can I tell the difference without plugging them into an amp??!!


Thanx

 

[Salas]

Innards of 12ax7s are smaller. The proper answer is 'get a curve tracer' but its not appropriate or functioning in this occasion. See labeled tubes, examine their innards and try to more or less match non labeled for internal sizes.

 

[ArtG]

Plug them into a tube tester, and compare them to a known tube. This should get you "in the ballpark", anyway. This should be helpful if you know that you are only dealing with ECC81, 82, and 83s. If you are not sure that the tubes in question are in this group, then your problem becomes more complicated. There are dealers and other experts that are good at identifying tubes by their internal structure, but I wouldn't think that your chances of finding such a person in Cairo would be very good.