CAUTION!!!
Unless I'm mistaken it appears you have the Primary and Secondary Grounds common thru the Aluminum Case BNC Grounds.
Usually you want those galvanically isolated.
Best,
So best to replace one connector (test device side) with an isolated bnc connector ?
So best to replace one connector (test device side) with an isolated bnc connector ?
Yes believe that should work out OK. Use the generator side common as the case ground and let the DUT side float wrt to the case and generator ground. An isolated BNC is probably the best solution for the DUT side.
Noted you have a nice Siglent DSO and AWG, you'll find some really interesting use for the Bode Function, and with the Iso Transformer this opens up all sorts of uses, see some of our posts wrt such!!
Keep us posted on your progress
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Best,
Great. Thanks for the advice, made that modification.
Oscilloscopes that offer Bode plotting make an injection transformer a desirable accessory. This thread and others inspired me to try to make one. I started with some Red cores, 27mm x 11.4mm x 6.3mm. The BW results were encouraging, but the low frequency performance was lacking. Internet searching turned up:
http://simprojects.nl/images/DIY_signal_injection_transformer.pdfRoland Van Roy describes a DIY transformer based on a Green core choke: Coilcraft CMT4-10-15. At $16.78 plus shipping it is a tad pricey and it is hard to remove the epoxy, but it is cheap compared to commercial transformers. The wire is from CAT5 Ethernet cable. It is worth the effort as the results are as Roland reported.
I made a mounting plate with BNCs and also tried a smaller shunt resistance (two resistors in parallel for equiv. of about 10 ohms). The original load resistor was 51 ohms. The bandwidth is now less but still OK for some use cases.
Neat! As per comment (which I had had also initially missed) you probably want a galvanic isolation on the DUT side, so you might want to switch one of the bnc connectors for an isolated one.