has anyone else experience this.....

i recently purchase a pair of mullards nos tube for my pv10 Conrad Johnson ....

they were used.............

A point of information: "NOS" = "NEW Old Stock" = unused.

Regards,
-- Al

TLS, thanks for the good articles, and the good points you provided in your post. As you and Bill_K indicated, the term NOS is unfortunately used too loosely too often. With the problem being further compounded by the existence of fakes, as Elizabeth pointed out.

As a potential purchaser, everything else being equal I would feel much more comfortable purchasing from a seller describing a tube as "used but tests as new" than from someone who simply describes it as NOS.

Also, I must say that personally I wouldn't want to be without a good tube tester (I have a vintage Hickok 800A), in part to minimize the possibility of component damage such as the OP has unfortunately experienced.

Best regards,
-- Al

Hi Tony,

Regarding calibration, all I can cite is my own experience. I've had the 800A for a bit more than 20 years, and used it lightly from time to time during that period.

I have a very large collection of vintage tubes that I use primarily in conjunction with my antique radio collecting hobby, having acquired them from a retired radio/TV service person, various auctions, etc. I can say with high confidence that many of them are NOS in the true sense of the term (i.e., unused). On almost all of the many occasions I have had to test some of those NOS tubes over those 20+ years, their Gm has measured in the general vicinity of what it should measure, according to the chart on the tester as well as older GE and RCA tube manuals I have. That gives me confidence in both the calibration of my tester and its stability over time.

Best regards,
-- Al