Tektronix 7854 Digitization Issue

Kyle Rhodes
 

Hi all,

I've got a wonderful 7854 acquired from a fellow list member, but I'm
having an issue with it. The digitization / storage function is not
working properly. Allow me to explain:

It acquires waveforms, but it's as though it's acquiring two different
waves, one at the correct frequency, and one approximately 1/5 the period.
I posted a video to YouTube showing an acquisition, you can clearly see
another superimposed portion of the wave across the entire sweep.

https://www.youtube.com/watch?v=vUq_e4OoAPA

The samples average out a bit if you run 10 or 100 acqs, but obviously it
doesn't result in a nice digitized waveform.

Also, the rendered text gets wonky during an acquisition. I'm not sure if
this is normal, or maybe it's related to the issue?

It's as though the time axis is not correlated properly with the Y axis
sample. Has anyone else encountered such a problem? This is a complex
unit, and before I spent many hours digging through the documentation and
learning how it works, I thought I'd ask for some starting points. Time is
money, and while I love working on this stuff, my day job involves using my
collection of equipment to produce other goods, so the less time spent
troubleshooting, the better. :)


Thanks,
Kyle

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