Hi Mariusz,
If you look at Chandu's post on Dec. 18, he mentioned just when T/R switch is NOT connected to the output of the pulser, he saw no visible distortion. However, when he connect the T/R switch to the output of the pulser, he saw the distortion. I don't believe he connected the transducer to the pulser yet.
Also, aren't all transducer come with shielded cable?
BTW, I did mention on the Dec. 17 post that the input impedance of the AFE need to match the impedance of the transducer.
Regards,
Charles