Using the Halibut Electronics CMC Test Rig, I hooked up the PackTenna PAK-103 In-Line Common Mode Choke (rated for 100 watts). The nanoVNA was calibrated using the Open/Short/Load on the Test Fixture.
Here are the results with some markers on the screen close to various ham bands:
Basically it provides the following CMC reductions:
- 35dB on 80m
- 39dB on 40m
- 34dB on 20m
- 30dB on 15m
- 26dB on 10m
Since I’ve often had issues with base loaded whips on 40m, this seems to be a pretty effective device, reaching commercial-level performance on 40m.
