Common mode current. Measuring effectiveness of choke

[Kevin VA3RCA]

Do you have a NanoVNA? Looking for new ways to use it?
Mark, N6MTS created this great video presentation on common mode current and how to measure the effectiveness of a choke you build.
Mark delivers a great explanation of what common mode current is and what the impacts are. He describes how to build a simple test jig to use your NanoVNA to measure the effectiveness of chokes we can build.
Using his test jig he demonstrates a number of simple common mode chokes, and graphs their impedance at frequencies across the HF spectrum!
Watch the video here:
https://youtu.be/3ReRu7Yt4Ao?si=jHpRsMWPg7kNUoe8

[VA3KOT John]

I wrote a piece on my blog about this technique too:
https://wordpress.com/post/hamradiooutsidethebox.ca/845

[VE3WI Dave]

I tuned in to N6MTS's talk in the Ham Expo back when he gave it.  Pretty good presentation.  I don't have anything as grand as his or John's test fixtures, just a simple one with RG-316 pigtails that avoids directly connecting to the Nano over & over, to protect those little SMA connectors.
73
Dave, VE3WI