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Trace cuts out on certain voltage ranges.

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Trace cuts out on certain voltage ranges.

Postby Baldilocks » Thu Jan 18, 2018 12:27 am

Hi.

I've got a 2205A that's a few weeks old. Looking at a trace that's a few MHz. The voltage is mostly around the 1V with peaks up to about 5V.

When I change the vertical range to 500mV or 1V I get a useful trace, but when I switch to 2V I hear a relay click, the voltage axis changes and the trace disappears. Further voltage changes to 5V and higher do not change the axis to match.

This is all pretty consistent but not absolutely so and there may be an effect from the X10 switch on the probe - but the wrong way round! I'm still trying to work that one out.

Any ideas please?

Thank you.
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Re: Trace cuts out on certain voltage ranges.

Postby Martyn » Tue Jan 23, 2018 7:43 am

Relays clicking when you go from 1V to 2V are normal for this device as internal attenuation is switched in.

Can you post a psdata file with the range set to 1V, and a file with it set to 2V, then we can take a look and see if we can work out what is happening.
Martyn
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Re: Trace cuts out on certain voltage ranges.

Postby Martyn » Fri Feb 09, 2018 1:09 pm

This will be due to the hysteresis associated with simple triggers. As you increase the range the hysteresis level also increases as it is a percentage of the full scale, the trigger condition no longer matches and the screen remains blank.

You can re adjust the trigger position so that it sits on a clean edge, change the trigger type to Advanced Edge and reduce the hysteresis, or turn on auto trigger and the trace will get drawn every second if there is no trigger match.
Martyn
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