From FB group Building Transistor Radios
Stuart Bca
The TO-18 and plastic versions use the same chip and therefore the specifications are the same, except for power dissipation and temperature derating. Both of those depend on the case, and the same holds true for the MMBT2222A in the surface mount package.
The TO-18 metal case is connected to the collector, so the capacitance is higher, and that might make a difference at high frequencies. If you want the same transistor chip but higher power, you can use the 2N2219A.
The complementary PNP version is the 2N2907A.
Remember any plastic cased transistor that is labeled 2N2222A is not the Real Thing. The original, true 2N2222A came in the TO-18 metal package, and is registered with JEDEC, that’s why it starts with 2N. Any other plastic transistor does not meet the JEDEC specifications. The 2N2222A transistors in the plastic package came with the middle lead bent out from the others. This was so the plastic cased 2N2222A could be plugged into the triangle shapes hole patterns of the metal cased 2N2222As. Their pinouts were the opposite of the 2N2222A plastic transistors.
All of this meddling with the numbers of the original metal can transistors has led to much confusion and wasted a lot of time. They should have never used 2N for plastic cases, they should have used PN or MPS2222A that most legitimate manufacturers used. But ask the average hobbyist and he can’t tell you any of this confusing information.
