Re: 7T11 horizontal memory

Albert Otten

On Wed, Dec 5, 2018 at 10:19 PM, cmjones01 wrote:

- in real time mode, it's hard to get a trace that makes sense. presumably the
50kHz-ish clock from the real time multivibrator limits the display to about
one sample every 20us, so some of the faster sweep speeds don't show a lot.
Even on the slower sweeps, the edges of my test squarewave exhibit terrible
risetime (about half a division) which is puzzling, and very different to the
behaviour in equivalent time. Maybe it's something to do with the recovery
time of the sampling head, or there's something amiss with the 7S11. I tried
adjusting the 'dot response' control and making sure smoothing was switched
off, but it didn't improve much.
Just to be sure that the fault is in the 7S11, you might check that the terrible rise time is also present when you use the 7S11 in combination with an ordinary timebase unit in stead of the 7T11.
You probably did not verify that you could adjust the dot response for loop gain one, it only "improved not much". I would check this first of all. The sampling head has an internal GAIN adjustment that could be too far off to correct with the 7S11 dot response adjustment.

You can probably tell that I'm new to the
7000-series sampling world. I regularly use my CSA803A/SD24 sampling setup,
but that makes it all so easy...
I followed the normal(?) route. I started with sampling units for the 564, then for the 7000 series and now I also have a CSA803A with SD-20 and SD-26. Still waiting for a good opportunity to buy an SD-24.


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