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High noise on a 4227

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High noise on a 4227

Postby kurt » Sat Aug 25, 2012 3:19 am

I've been testing my 4227 Picoscope with a pulse generator, and noticed a dramatic difference in the quality of the traces obtained at the 2 V range compared with the 5 V range (and higher). When you switch from 2V to 5V, the noise level goes up by at least a factor of ten, and my signals get an additional DC offset of -60 mV. In addition, the DC offset fluctuates by ~10 mV over the span of a few seconds. If I didn't know any better, I'd say that there's a floating ground in the scope.

Is this normal? I realize that it's to be expected that you take a noise hit when you go to higher ranges, but this is almost unusable.
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Re: High noise on a 4227

Postby Martyn » Tue Sep 04, 2012 6:26 am

Are the readings you are getting within the specification 1% of full scale (20 °C to 40 °C) ? If not let us know.

The reason there is a change between 2V and 5V is due to the switching between different input circuitry, note the relay click as you change vertical scales.
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