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Input stage overshoot

Posted: Wed Apr 08, 2020 3:26 pm
by cgo75
Hi,
When I connect the analog output of Red Pitaya STEMLAB 125-14 to the analog input of the same device (loopback), using a BNC cable (no probe), I get the following ( HV, 2KHz, 2 Volts peak to peak) :see 2nd picture

In // I connect the output of Red Pitaya (STEM 125-14) to my oscilloscope (Hantek 4102C) with the following result : see 1st picture

It seems obvious the the input stage of Red Pitaya is overshooting. I went through the forum and found a previous thread named "Input Stage Inerfections" but I didn't see a clear and usable fix for this problem.

I do not use any probe, only straight 50 ohms cables with BNC connections. I try to load the output with a 50 ohms load without any change (obvious).

The unit is a new one delivered in 2019. It replaces a previous unit that didn't show the same issue (as far as I remenber).

Please help

cgo75

Re: Input stage overshoot

Posted: Tue May 05, 2020 7:19 am
by redpitaya
And what happens if instead of the regular cables that you used on Red Pitaya, you are making the connection with the hantek probe cable?