71.194.241.37
In Reply to: RE: Agree... posted by TUBOS on May 30, 2009 at 06:36:01
Thanks for sharing that info!
Just a couple comments if I may:
1. Gm variance from 2200 to 3000 uMho is a difference of nearly 40%. That's typical, and is about the same as I find in other small signal NOS. It's also what I find in new production.
2. 5 ma to 8 ma is a difference of 60%.
I point these out because often I see comments about how new production tubes don't have the "tight specs" of NOS tubes. Well, 40% variance and 60% variance hardly qualify as "tight".
I also appreciate you sharing this:
"A few obviously used tubes were also tested, with many at the low end but with some testing at the high end even with significant visual indications of use present."
SO true! Tester results - any tester - cannot be used as the sole criteria to judge a tube's "newness".
Finally, you wrote:
"...as line voltage changes caused a shift in Gm and Ip readings. This is probably linked to changes in filament voltage and plate voltage during test (triodes sensitive to plate V)"
Yes! A very cogent comment, thanks for sharing it.
Great post, very useful data - thanks again!
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