---
title: Homebrew common mode choke
summary: |
  A simple and quite tiny common mode choke that I built for my
  portable operations.
coverCaption: My selfmade common mode choke placed into a neat plastic case
  with BNC connectors.
date: 2023-10-26T13:36:26+02:00
lastmod: 2024-09-28T23:48:06+0000

showBreadcrumbs: true
showReadingTime: false
showWordCount: false
---

So this is basically a 140-43 toroid with 9 turns of RG174 connected to
BNC connectors.

It works very well and I have made two measurements recently.

{{< figure src="logmag_through.png" caption="The maximum loss is on 10m around 0.2dB" >}}

{{< figure src="logmag_outer.png" caption="It attenuates common mode current with more than 20dB" >}}

I find this okay for now but I still wonder if this can be made any better
(maybe 30dB attenuation?). Would I benefit from even more attenuation?

I will probably find out on another day.