Back to Bob K4TAX I had a common mode current problem when I lived in Virginia and ran 100 watts barefoot, and it came as I could not do a significant angle away from the antenna --- which I eventually solved.
I really do love the OCF idea. Through modeling it and patterns and then careful selection of trees for directionality, I have been able to land the lobes on Europe, South America, and East Asia for 40m, 20m, and 15m with upwards of 8 dBi --- not too shabby for a wire antenna. I have some LMR-400 and RG-9 B/U here and plan to change out the coax. I no longer expect that work to solve the issue, so I am looking at baluns. While it is a change back from a current balun to voltage balun, I must may do it. Thanks for all the good wisdom, guys! On Mon, Jun 1, 2020 at 6:33 PM David Gilbert <[email protected]> wrote: > I had an antenna for 160m that had a fairly high SWR at the feedpoint, but > was easy to match to 50 ohms with a series inductor less than 30 feet > further down the line toward the shack. I put a common mode choke per > K9YC's designs at the antenna feedpoint, though, and even though it was > actually two chokes in series (two large cores with separate windings) that > should easily handle 5 KW under matched conditions, at 1.5 KW it heated up > in less than two seconds to put the QRO Tech HF-2500DX amp into a fault. I > could have moved the choke to the shack side of the matching inductor, but > I decided it was best to just fix the antenna. No problems after I did. > > Common mode chokes don't need high saturation current to get hot (and > that's rarely the problem anyway) ... high SWR voltages work just fine for > that. And at high power it can happen in a very brief period of time. > > Everyone stay safe, > Dave AB7E > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] > -- 73 de Ted Edwards, W3TB and GØPWW and thinking about operating CW: "Do today what others won't, so you can do tomorrow what others can't." ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
