has anyone else experience this.....

Al, you're welcome. Always glad to provide helpful information.

The Brent Jesse site also has a lot of other good info about vintage tubes, as well as some instructional videos identifying certain vintage tubes. The following websites have many pictures of vintage tubes that may also help with that vintage tube identification.

tubeworld

tubemongerlib

I acquired the Brimar 12AT7's many years ago that I previously mentioned, and for quite some time was unsure about them being authentic, as they were different from all other pictures of Brimars I found. After finding a picture on the Tube World site, I then felt they were a real vintage tube. This was also confirmed when I allowed a few local friends to try them, and they did not want to return, but asked to purchase them.

BTW, I also have tube testers, a B&K 600 for quick simple testing, and a Hickok 752 for more serious testing. Although the Hickok seems to work reasonably well, I am curious about your thoughts on calibration of this tester.

Tony

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

Al, thanks for your comments, as that makes me feel better about my 752. I have had it for quite a few years, and over that time the results have always seemed to be consistent.

Also, some of my tubes came from my dad's shop, as he was a radio/TV serviceman, with many others coming from different shops in my area. I also collect some antique radios, mostly Zenith, and some HH Scott tube gear.

Cheers,
Tony