The curve tracer seems to work, but the out and back I-V curves do not lie
on
top of each other and the whole family of I-V curves seems to "wobble" a
bit
on the screen.
Does this sound familiar? Any ideas?
That sounds about right. It depends on the collector base capacitance, but
you can end up with "looping" where this capacitance has a significant
effect, particularly with medium to high power transistors. In fact Tek
recommended a method for estimating this capacitance; you add external
capacitance and when the loop doubles, the external value about equals the
collector base capacitance.
The wobble is mainly visual - if you reduce the number of base steps, you
will see that the wobble disappears every other step.
Also switch to the higher step generator rate to reduce trace flicker.
Craig
