Ditto the above.I have several 30-40 year old tubes that test to new tolerances.
Tube Measurements?
Once a tube is measured, do they stay the same over time? that is, if I buy an NOS tube that measures xyw today, will it still be the same 5-6 years down the road when I need to use it. I wonder about this in cases I want to buy some NOS that are running out and what to buy now and use later.