Rudge wrote:

I need a T039 NPN transistor with an 80 volt BVceo rating such as a BC142.

My nearest stockist holds the BC141 which has a BVceo rating of 60volt.

If I buy a BC141 and test the breakdown voltage, what are the chances that
it will exceed 80volt?

No idea, but specific devices are indeed selected by parameters from a general
device group by testing, so you're in with a chance.

If the yield at higher voltages was good for that batch, you may well find that
the '141 may meet a '142 spec.

What application is it used in btw ?

Graham