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12AX7/LPS Sovtek - I am very confused, please help

I just purchased a brand new 12AX7. I tested it on some of my emission type tube testers I have, namely:
B&K 606
Sencore; TC-28, TC-162
Eico 625

testing this tube makes the needle move 1/4" off zero, some make the needle go to the middle of the "replace" and then drops down to about 20.

This is a brand new Russian Sovtek 12AX7/LPS, I find it hard to believe it's bad.

I tested a 12AX7 from 1969 and it read very good on all my testers.

I contacted the merchant that sold it to me and he gave me a very long winded story about what is good and bad and he tests them on a Hickok and was leading me to believe all my "emission" tube testers were not checking it correctly.

I told him I can't understand why I can't use a vintage emission tube tester to check this NEW 12AX7.

Is he right? or is the tube very very weak?

Please help me with this.

Thanking in advance.

-TommyR
tommyr
mrderrick
292 posts
 
I have found that sometimes grid emmision testers do not provide the same results as mutual conductance testers. Tubes that tested replace or bad on my grid emmision tester often have very high gm values with my mutual conductance tester. How does the tube sound? Thats the ultimate test.
elevick
2,636 posts
 
You may have to buy a second one? If that tests the same, the dealer is right. If not, he owes you one.
jomik
11 posts
 
I had this happen too and asked Brent Jesse at audiotubes.com about it. On b&k testers including the 606, a new 12ax7 will test at 25%.
mechans
3,048 posts
 
It sounds like a simple dud. I hear from experienced dealers of new tubes that about 5% of them are rejects if Russian.
I agree check it by using it but check it for shorts first
tommyr OP
1 posts
 
hmmmmm, my new Grove-Tube 12AX7 comes up to 25% on my b&k 606 but the 12AX7/LPS Sovtek barely moves the needle.

-TommyR
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