WMYCONGCONG 40 PCS Coaxial Camera Video BNC Male and Female Balun Connector with Solderless Screw Terminal for Coax Cat5 to CCTV (2 Kinds)

You would think that it would be impossible to screw up something as simple as a BNC connector. But you'd be wrong.I've been using these to connect pairs of probes for a data-collection project. And for most of a week, was tearing my hair out trying to figure out the source of strange dropouts - probes becoming intermittently disconnected, and a lot of variance in the data. Finally one failed completely, and after replacing all wires involved, I tested continuity across the BNC connector. None at all on either side.Moreover, whatever conductor connects the screw terminals to the BNC connector itself introduces substantial resistance. The graph above measures voltage across a medium whose conductivity should decrease over time. The spike where the voltage goes up is the point at which I stopped collection, removed all the BNC connectors from the circuit, and simply capped the wires together instead. The voltage through the circuit jumps considerably, and the noise goes down considerably.I have no idea what materials were used to make one of these (though I might crack one open to see), but they are absolute junk. Do not buy.