EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: avhoboken on January 06, 2018, 12:18:32 pm
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Hi,
I recently bought the Rigol DS1054Z and the DG1022Z and experimenting a bit to get to know them better. I also bought a second BNC cable to connect both channels to the scope.
The question I have is regarding the separately bought BNC cable, when choosing a sine or ramp wave, all looks good. When choosing a square wave it seems that this cable gives a spike at the beginning of each period, so for example when then generated wave has a Vpp of 5V, the scope sees a Vpp of 7.08 V. And the overshoot is around 50% instead of 1-2% with the included cable.
I don't have this issue with the included BNC cable. I swapped cables to be sure but behavior is only with 1 cable.
Any explanation for this?
Thanks for any help or feedback.
Alex
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The 1022 is a 50 ohm Z. The 1054Z is basically a 1M ohm z,
so you need a thru terminator on the 1054Z to make it look like
50 ohms. So transmission line (the cable) is properly terminated.
https://www.pasternack.com/50-ohm-feed-thru-load-terminations-category.aspx (https://www.pasternack.com/50-ohm-feed-thru-load-terminations-category.aspx)
Or build a DIY terminator.
https://www.eevblog.com/forum/projects/home-made-feed-through-terminator-for-bnc/ (https://www.eevblog.com/forum/projects/home-made-feed-through-terminator-for-bnc/)
http://web.cecs.pdx.edu/~greenwd/xmsnLine_notes.pdf (http://web.cecs.pdx.edu/~greenwd/xmsnLine_notes.pdf)
Regards, Dana.
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Dave's done a video on traps for young players explaining what Danadak's said about the correct termination.
https://www.youtube.com/watch?v=PPgxFd97taY&t=496s (https://www.youtube.com/watch?v=PPgxFd97taY&t=496s)
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The output of digital signal generators is often inaccurate/poor at low output levels, so an attenuator is a good idea.
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Thanks for all the help, much more clear now :)
Alex