Clamp-on Common RF current meter

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To improve my station's transmission effiency and reduce its suspectibility to feedline noise pickup, I decided I needed a means to measure common mode RF on the feedline.

The design is rather basic and taken from here:

http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm






I ended up using a germanium diode instead of Schottky because that's what I had in my junk box. One day I may upgrade to Schottky if I ever buy any.



As I suspected, there is common mode current flowing on my HF antenna feedline. This is not a big surprise to me given it's an OCF dipole.


What if I add 10 clip-on ferrite chokes to the feedline?


This is a substantial, if incomplete, reduction in common mode RF!


I decided to go ahead and choke the antenna at the base of the tree supporting the feedpoint.



This works well on 40 meters and up!



80 meters still needs some work, though.




Created 23 April 2020
Edited 23 April 2020
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