Jim, I apologize: I made a typo in my post. It should have said "...the highest choking IMPEDANCE is usually obtained with an air core choke (coax looped with or without some form like PVC)". Maybe this is an over-statement, but of the few chokes I have tested, air core chokes made with just standard coax have shown the highest net impedance, but also the narrowest useable BW because of the high Q. I have seen these baluns used in countless QST articles over the years, and even as part of some commercial antenna designs.
In my previous posts, I tried to emphasize that choosing a choke to reduce common mode current needs to be a system level process. Because of the importance of the resonance problem, I explicitly stated that adding a choke can either reduce, have no effect on, or increase the common mode current. I appreciate the points you make regarding the use of a ferrite core that yields wide BW and high resistance. However, there are those that argue against this approach by claiming that there is no need to burn up the common mode energy in the choke resistance, when you could just as easily use a high reactance choke to reflect it and re-radiate it out the antenna. However, the proponents of this approach either don’t discuss the potential resonance problem, or state that as long as the choke’s resistive component is greater than 5x the antenna feed impedance, you don’t need to worry about it. Bill N0CU -- View this message in context: http://elecraft.365791.n2.nabble.com/Choking-KPA500-and-testing-a-box-of-unknown-chokes-tp7631010p7631077.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
