Re: Tek 576 noise and looping

Brad Thompson
 

peter bunge wrote on 11/15/2019 3:27 PM:

No, I have not been working on the 576 curve tracer for 8 years but i have
been curious about the looping for at least that long.
Thanks for your explanation which I tested by comparing curves with slow
and fast transistors. I had some trouble trying to find a couple with
matching gain but the high freq (900 MHz) transistor performed perfectly
with nice curves at low current. On the other hand the slow transistor had
huge loops. I would like to concentrate on the noise problem next. It mat
be finger trouble.
<good info snipped>

Hello--

This is a long shot, but I wonder whether there's a thermal issue involved? If the
device's die is poorly attached to its header or if there's a poor thermal connection between
internal lead wires and the die attachment(s) that might cause an offset between the
increasing and decreasing base current.

If it's a leakage effect, I'd expect that germanium transistors (remember those<g>)
would show fat loops.

73--

 Brad  AA1IP

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