Well they are NOS so I'm not sure it would do any good to test new 7308 as they wouldn't be the same.
For many tube testers, there is a level established as a standard value for a new tube. For 6SN7s on my tester, that is about 2200 (obviously a different scale than the tester being used here).
If a tube tests below this value then it is probably not new (tubes can test above this value). I was asking if there was such a level established as new for the tester being used here. If you are sure these are NOS, then forget about it.
On each tester there is also a value below which a tube is not considered usable. I was suggesting that's what the seller was indicating with the number to the right of the slash (13). The number before the slash is the reading he is getting for the tube being tested (18). Therefore, these are testing 18 where the minimum usable is 13.
Because each of these tubes has two triodes, the seller is reporting the test value followed by the minimum usable value (tested slash minimum). In every case, the triodes here read exactly the same (18).
As Steve mentioned, the scale used here is some sort of relative scale. I disagree with his interpretation of the results though and I think instead that every triode tested identically at 18 units (whatever they are).
Although I think I have this right, I could well be wrong, so you should ask the seller exactly what these numbers mean relative to the tester he is using. That's the only way to know for sure.
