Agreed. I thought I made that point clear. And it's not just common-mode currents. It all depends upon the load. A "dipole" antenna, for example, is seldom exactly the same distance from surrounding objects on each half, which will "unbalance" the load and so unbalance the currents on the feed line.
As Don points out, the currents emanating from the SO-239 connector are balanced when you consider the current flowing on the outside of the center conductor and on the inside of the coax shield (what goes on along the outside of the shield is a totally different situation - RF flows along the surface of a conductor so completely different currents can appear on the inside and outside of the shield, assuming it's a good shield.) 73, Ron AC7AC -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ian White Sent: Friday, February 5, 2016 2:24 AM To: 'Wes (N7WS)'; elecraft@mailman.qth.net Subject: Re: [Elecraft] Balun suggestions Wes's point is that twin feeder is not automatically "balanced" - very far from it! Twin feeder happily supports both differential (equal and opposite, balanced) currents and common-mode current at the same time. So, in the real world, there is no such thing as "balanced" feedline unless YOU actually DID something to FORCE it to be balanced. And the way to do that is to insert a common-mode choke that enforces equal-and-opposite currents at that particular location... though even then, it can do nothing to prevent the regrowth of common-mode current elsewhere along the line. 73 from Ian GM3SEK -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Wes (N7WS) Sent: 05 February 2016 00:18 To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Balun suggestions I just pinched myself; I'm not dreaming and it's not April 1st, so I guess you're serious. You are also so wrong on so many points, I'm not going to waste time trying to refute or correct them. Jim, please ignore everything said below. Wes N7WS On 2/4/2016 3:05 PM, Ron D'Eau Claire wrote: > Your feed line will do the job by itself so no additional "balun" is needed. > Keep in mind that a 1:1 balun is really just a length of feed line, > usually wound on a toroidal core to make the required length shorter > than if it was in open air. The "old-school" baluns were just a pair > of air wound coils. > > If your balanced feed line is at least 1/4 wavelength long, the > currents will be "balanced" (equal and out of phase) at the antenna. > That assumes your antenna is perfectly balanced to provide a perfectly > balanced load, which "balanced" antennas almost never do. There are > just too many variables. So expect excellent results even with shorter > feed lines. The amount of radiation (or pickup) from the feed line > even at the rig end is small in any case. > > Connect one side of the open wire feed line to the KAT100 SO-239 > center pin and the other to the KAT100 ground terminal. > > 73, Ron AC7AC > > > > -----Original Message----- > K2/100 and KAT100 here. > > I am changing around my modest antenna configuration now. I have been > using the K2/100 with my AH-4, and now wish to use the KAT100 with > balanced feedline antennas. > > What balun, homebrew or commercial, if any, should I use? I almost > always run 5 watts, all CW. > > 73 de W6OGC Jim Allen > > > ______________________________________________________________ > 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 > w...@triconet.org > ______________________________________________________________ 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 gm3...@ifwtech.co.uk ______________________________________________________________ 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 r...@elecraft.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
