I'd like to measure a Wheatstone bridge with a lock in. The bridge has something like 20kOhms resistance. I would like to measure with some fairly high frequency like 50kHz but my cable capacitance is causing trouble and low passing at 10kHz or so. Two questions: 1) What would you recommend cable wise? The normal 6mm BNC cables have a lot of metal in their shield. Would twisted pair wire lower the total capacitance? Would shielding around the twisted pair influence the capacitance? Are thin coax cables better? 2) I am also experimenting with a pulse transformer, and I am thinking about buying a new one. The manufacturers specify "impedances" of 600Ohms for example. I imagine that is for an old 600Ohms wave impedance cable standard. I measured my transformer and it only has about 40 Ohms DC. What do the manufacturers specify? Impedance is frequency dependent isn't it? Where can I get pulse transformers that work at ultrasound frequencies (audio ones seem to be fairly easy to get)?