[Elecraft] OT: Difference between PN2222 and PN2222A?

[Stuart Rohre]

Looking at the A suffix 2222, it appears they are graded units having a 
higher breakdown voltage across the elements.  It should work anywhere a 
2222 without suffix is specified.

The PN 2222 should work in PN 2222A circuits that do not exceed its element 
voltage ratings, which if you are building to a 12 volt or less supply 
source, would be any application.

-Stuart
K5KVH