have an old transistor and need to find a way to identify it

i have an old transistor and there are no markings identifying what it is.
is there a way i can test it to find out what a good replacement would be. i think it works fine but i need more and i have no way of finding out what the transistor is. so i was hoping that there is a transistor tester or maybe someone i could send it to who could tell me what it is and where i can go to get a good substitute.

You might be able to suss out more about it with a curve tracer, may not be worth the trouble.

If you know the max power supply it see's and general circuit application you might be able to make an educated guess about a generic replacement.

JR

i've read this:
Probably the only way to truly identify it is to crack open the case and find the marking on the substrate under a microscope. Which will destroy it in the process

does anyone know how i could do this. is there a good process for doing this?

I wouldn't count on finding any identifiable markings on a transistor substrate.. these are usually quite simple and all business.

I used to grind to tops off of old TO3 metal can transistors to look at why they failed. With old simple technology you could look for a melted base or emitter wire indicating overcurrent. Or perhaps a visible sink in the collector region where perhaps a voltage spike punched through and the local heating caused some melting before fuses opened.

I still think your best chance of ID is curve tracer or reverse engineer from actual circuit.

JR