2 probes differs

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oxd
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2 probes differs

Post by oxd » Fri Aug 17, 2018 9:30 pm

Hi,
I measure the same signal with the same probes but the signal differs in a vertical offset.
Is it correct to set the "Axis Scalling Offset" to "-0,30 %" on channel B to fix it for ever or is there another preferred way? It is normal that the channels differ?
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bennog
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Re: 2 probes differs

Post by bennog » Sun Aug 19, 2018 7:24 pm

if it is a 8 bit scope then 1/256 th is about 0.39 percent so then this is within limits.
but when you use resolution enhancement then this can be lower in theory.

but if it is a 2000 series scopen then the spec gives a 3% accuracy on DC values.

Benno

Martyn
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Re: 2 probes differs

Post by Martyn » Mon Aug 20, 2018 7:44 am

Depending upon the scope model you have there may be an option to Zero offset each channel, check in the channel options menu or let us know the scope model.
Martyn
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oxd
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Re: 2 probes differs

Post by oxd » Sun Sep 02, 2018 5:04 pm

The model is 2207B. Yes, that's in the 3% accuracy on DC values. I thought the channels should be somehow hw calibrated to be the same in the DC offset.

I can manually fix that by "Axis Scalling Offset" set to "-0,30 %" in the probe B settings. So is creating a custom probe with DC offset set and always using it the permanent fix to this or is there a hw trimmer inside or something like that?

Martyn
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Re: 2 probes differs

Post by Martyn » Wed Sep 05, 2018 10:56 am

Use the Zero Channel Offset button in Channel Options window, which will do this automatically for all ranges, so you don't need to do this manually using a custom probe or scaling.

Remember this will need to be performed each time you use the scope as the offset may change due to environmental factors.
Martyn
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