Common mode current and chokes

Posted by Fred C (W6BSD) on Feb 23 2020

Tech day in Sacramento

This Friday, I was invited to Sacramento to give my presentation on common mode current, what it is, and how to block or prevent it using common mode chokes.

Once a month, Jeff (AK6OK) and Craig (N6YUV) organize a meetup they call ham tech day. A bunch of hams from the Sacramento Valley meet to talk about anything technical related to ham radio, drink coffee, eat doughnuts, cookies, and laugh.

There is always an exciting topic for these meetings. Last time I went, Jeff gave a presentation on DMR and how his repeater was setup. I also had the opportunity to play with a Rohde & Schwarz spectrum analyzer.

At the last Friday meeting, a group of people was learning and programming code-plugs for a DMR radio. A second group was fixing a power supply on a Kenwood TS930. And the third group was learning about common mode currents and chokes.

If you are in the Sacramento Valley and want to contact that group of people, you can go on the K6IOK repeater (145.130 Mhz - PL 114.8Hz). If you are anywhere in the world, you can contact them on the SacValley DMR talk group (311416).

Here are the slides from my presentation:

Common mode current and chokes presentation
Common mode current and chokes presentation

 Chokes      UNUNs