Re: 7A29 overshoot


Nenad Filipovic
 

On Sat, Dec 30, 2017 at 10:33 PM, cmjones012003 <chris@stumpie.com> wrote:
I looked at the 7904A calibrator output on my sampling scope, which
should give as accurate a picture as I can manage, and that shows a bump
just the same:
https://photos.app.goo.gl/F3MUCs38rUW5e9my1
<https://photos.app.goo.gl/F3MUCs38rUW5e9my1>

Thanks for the image Chris, so those calibrators are more-less the same.
I have posted photos from this thread to a group album named "7A29
feed-beside compensation adjustment", you can add your image(s) to it if
you wish, the album is public.
Hope you also manage to fix your units in a similar way,

Best Regards,
Nenad Filipovic


On Sat, Dec 30, 2017 at 10:33 PM, cmjones012003 <chris@stumpie.com> wrote:

On 30 Dec 2017 5:12 p.m., "Pjotr Tolstiakov" <ilmuerte@gmail.com> wrote:

Now that fear of ruining a good calibration was out of the way, I got
medieval on feed-beside COMP 1-7 plus GAIN and here's the result:
http://www.nfilipovic.com/content/electronics/7A29_1kHz_
Calibrator_After_LF_
Calibration.jpg
Adjustments interact and take a dozen of loops to get right. Now GAIN is
approx. midway and everything looks much better. There is some residual
overshoot left:
http://www.nfilipovic.com/content/electronics/7A29_1kHz_
Calibrator_7854_Overshoot.jpg
but this is far into the hi-freq territory. 7A24 showed an almost identical
overshoot, I moved them both to a 7104 where the result was very similar.


Great result! That's a really worthwhile improvement. I think that
100ns-ish bump just after the rising edge may be there on the calibrator
output, if the 7854's is anything like the 7904A's. I looked at the 7904A
calibrator output on my sampling scope, which should give as accurate a
picture as I can manage, and that shows a bump just the same:

https://photos.app.goo.gl/F3MUCs38rUW5e9my1

I hope the photo is visible.

Chris



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