On Sat, Nov 24, 2018 at 03:56 AM, tom jobe wrote:
What you are seeing on your 577 with these settings is as good as
anything I have ever seen on my 577. The different behavior with
different amount of steps is very normal too. Depending on settings and
how many traces you are showing, it can freeze the display and have no
flickering of any kind. I believe that extra line you see is just the
base zero line, because when you count the traces there are 11 of them
when you have the 577 set to the maximum of 10 traces. The base line
also comes from with 'dot' at the lower left of your screen, and I
believe the 'dot' is the zero point for the display on both the vertical
and horizontal axis.
I have seen the kind of traces you have been worried about, but did not
understand about testing the transistor with very low current.
I think that Chuck Harris has once again saved us with his excellent advice.
Thank You Chuck!
tom jobe...
On 11/23/2018 8:37 PM, Wolfgang Schraml wrote:
OK. I uploaded another series of pictures. Same folder:
/g/TekScopes/album?id=79121
I used a different 2N3055 than in the previous pictures.
Settings:
- Vertical: 50mA/Div
- Horizontal: 5 Collector Volt/Div
- Step/Offset: 0.1mA
- Max Peaks Volts: 25V
- Variable Collector %: 100%
- Series Resistor: 120 Ohm
I took a picture for every step increase. What's interesting is that "odd"
numbers of steps seem to have less of the retracing issues than "even"
numbers. The flickering of the display is also more pronounced with even
numbers. I ran all samples with the fastest step rate.
Another questions since I have no experience with this instrument - is it
"normal" that I get two traces even with just a step count of "1" ("number of
steps" knob fully ccw)?
Thank you again, Wolfgang
Thank you everyone for the feedback. Like I said - have no experience at all with this amazing instrument and would have probably torn the whole thing apart again chasing an issue that doesn't exist.
I ran through the adjustment procedure last night and all except the "Polarity Positioning" when switching back from "Display Invert" to " Display Norm" (Adjustment Procedure, step 15 (f)) could be brought within spec.
The only remaining issue is the storage feature not working well - very weak overall and only works around the center of the screen. Not worrying about that right now, not planning to use storage.
Thank you again, Wolfgang
