[Amps] Transistor Lifetime

[Dan Hearn]

I have  several  NPN RF power transistors which were acquired about 10-12
years ago. They were new at the time and are still in the factory sealed
packages. Some are matched pairs. Included are MRF454, MRF421, MRF422MP . Do
these deteriorate in storage? These are all in ceramic cases. Would you
expect to see any deterioration in PA output with use over a number of years
? How about epoxy cased transistors?
73, Dan, N5AR