Thanks,
Yes, we need to actually take in our own splitter transformer and ask them to connect it up to the LISN outputs upstream of their Network analyser.
Does anyone know of an offtheshelf splitter transformer that’s good for this use?
I looked through minicircuits.com and microcircuits.com and they have nothing.
The other problem is that we don’t know what kind of RF connections they are using. I suppose we will have to ask them, but they have always pretended not to know what we were talking about when we previously asked them about splitting the LISN output into CM and DM.
The problem with us winding our own splitter transformer on a torroid is that we may end up with too much magnetising current and thus distort the signals. Alternatively, we may get too much interwinding capacitance and again distort the signals. We don’t have a network analyser to use to check against such ills of RF design.
The following “LISN MATE” device…
LISN MATE
https://www.tekbox.com/product/TBLM1_LISN_Mate_Manual.pdf
…..splits out CM and DM, but it needs there to be two LISNs, and the test house we go to has a fixed set-up, with just one LISN.
In the following diagram….
https://imgur.com/dc7mAyj
…we assume that the CM output is referenced to earth ground?
..and that the DM output is just the output of the secondary terminals?
I think the problem for us will be insertion loss, but at least we will get an idea of what proportion of the failure frequencys are CM and DM….that will really help.
I must admit it amazes me in this day and age that the computerised Network Analysers at EMC test-houses can’t measure live and neutral at the same time and thus give a separate CM scan plot and a separate DM scan plot…without needing a splitter to be put in there.