Recently I have focused back to my experimental work on BALUN and Common Mode Chokes, also known as RF and Noise Suppressors. In past five years I have wound hundreds of Ferrite toroids and did countless measurements. I have learned a lot from various ferrite manufacturers as well as from some known amateur radio experts on this subject. My conclusion was that there is so much room for improvement in design of BALUNs and Chokes as well as broadband transformers. So, I set out to make better products compared to ones offered on the market which, by the way, after evaluation and measurements, in most cases are pure “snake oil” or “Mighty Fine Junk”.
Average HAM or new comer in a hobby have no way to learn what is good or bad antenna product, it is up to these well established makers of the antenna products to set the bar for good or bad. Minority of us , which do know and understand the complex problems of antenna designs, do try to promote the knowledge and set things right but other then some forums and email reflectors there is no access to vast HAM community on this subject.
Over priced products, some times not working at all, only pushed me harder to work on properly designed and tested models. The results are amazing!
Not only that I validated the work of known experts on subject of Common Mode Currents and BALUN designs, I set the bar higher and designed some amazing products. Oh, do not think that I am selling a story, nicely packed in technical lingo, but in fact I am only one which has measured (precisely) and published a whole data on each product I design. Yes, there are some providing a basic data such as Common Mode Impedance Magnitude (Zmag) but nobody has produced a complete data of complex impedance to show a real picture of how the product works.
I have evaluated a products so badly designed that I could not comprehend how in a world they managed to screw the things so bad. Anybody knows how to buy a popular type of Ferrite toroid an wind a 7-12 turns and get average results. They failed to do even that. These guys are claiming a tens of thousands of Ohms of Common Mode Impedance while their product has less then 200 Ohms on some bands with only few Ohms of resistive part (Rs) and rest of it is reactive inductive(+/-jX). Some are claiming that their product works from 1-250 MHz but in reality it works somewhere above 30MHz and not in any amateur band. There are dozens of examples of these bad products, yet, they are being sold even by major amateur equipment distributors world wide. Well, it is not their fault, they just have no enough choice.
So, I have few more stuff coming but that is for another post, in the meantime explore a bit my products such as CMC-230-5K , a cascading chokes, which has dominant Resistive impedance from 2-30MHz.
Just to give you a hint, only Resistive part stops and Dissipate the Common mode currents and suppress the noise buildup on your cable by various sources for sure, reactive (inductive/Capacitive) part of common Mode impedance can make things even worse. On that subject some other time.
Stay tuned, more is to come….
Danny Horvat, E73M / N4EXA
