common mode rejection noise choke

[W4AMV]

There are a couple of threads on this item and some good notes on building. One item not seen is the rejection provided depending on the choke placement and orientation. Though this may be of interest. My cocktail of ferrite material is different than some others, like Clifford Labs and AMRAD for low frequency receivers. I was able to achieve better than 40 dB CM rejection (1-30 MHz) but required the orientation shown in the picture. Reference level is 0 dB. Yes, coupling has a big affect, see final result in an enclosure. To achieve better than 20 dB below 100 kHz will require larger size ferrite with permeability of 5-10K. Alan