Holy Smoldering Lumps of Teflon Batman!

26 Sep

Or at least that is what I thought after reading recent choking articles found on the web that suggests one cannot possibly use common mode choking with balanced lines.  I have been using balanced feedlines off and on over 40 years or so and only recently discovered how profoundly common mode chokes can affect positive change in RFI and noise on my transmission lines. So here I sit, after all these years, I find a means to have an efficient balanced feedline, a broad banded antenna system, lower noise in my receiver and best of all, a reduction of RFI in my shack that can only be called miraculous and some guy is out there telling everyone its a bad solution? Whoa old paint.

Here is a picture of my first feedline that used common mode choking being tested with approximately 500 watts RF into a choke designed for 200 watts. I really wanted to stress test the solution I was using.

Measuring Temperature while Xmitting Was I able to raise the temperature? Sure-a little but recall the design was intended for 200 watts. With normal 200 watts through this choke no heat was detected. Any loss would show up as heat as there is no other place for the energy to go if it was lossy to the point of destruction as this fellow was predicting.

I have since built a Common Mode Choke  designed for higher power. I use this one with my LK 500-ZC amp at approximately 500 watts daily. I measured this choke as well and it never achieves any temperature other than ambient even following a 1 hour CW practice schedule. This design has been in service for over a year now. I use four of these Common Mode Chokes in my balanced feedline.

QRO Choke

QRO ChokeI hope this shines a little light on the use of Common Mode Chokes in a Balanced Line environment.

Thanks for reading my Blog. Best, Chas W5PG

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Posted by on September 26, 2009 in Radio


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