On Mon, May 21, 2018 at 07:09 pm, Raymond Domp Frank wrote:
Your nice old 485s come equipped with graticule markers specifically
for rise time measurement.
Hi lop pol (and Siggi),
I decided to repeat your experiments as best I could. I used one of my
PG506'es. I know it to have a rise time of about 750 ps. I used an S-52 pulse
generator head as a pulser. It has a <= 25 ps specified rise time. It produces
a complicated waveform but is quite usable for this purpose.
I thought that I could conclude rise times from your pictures, even though you
didn't adapt the signal to use the intended markers (Siggi indicated that to
you).
As it turns out, my screens look comparable to yours with the TD signal.
However, looking back and forth between the two, I'm not sure about my rise
time readings with these "wrong" screen amplitudes. It could be anything
between 600 ps and just under 1 ns. It turns out that I'm much worse than I
thought at estimating the 10% and 90% levels when not using the marker lines.
With regard to the PG506 signal, I'm pretty sure now that you did use the
level adjustment as I suspected in my earlier post. It's the only way to get
the screen amplitude in your picture, with the 'scope on 10 mV/div and a 10x
feed through attenuator. It explains the slow rise time.
For me, your pictures now seem "credible" and so, all is well again...
Raymond
Thanks for participating!! No one ever wants to play with me. I love this group :)
