Thanks to all who replied to my coiled-coax choke question. Good ideas, all; and I am off to study what K9YC has written on the subject . . .
73, Ted KN1CBR > > > >------------------------------ > >Message: 6 >Date: Mon, 20 Oct 2014 19:48:29 -0700 >From: Walter Underwood <[email protected]> >To: "[email protected]" <[email protected]> >Subject: Re: [Elecraft] Coiled Coax Choke >Message-ID: <[email protected]> >Content-Type: text/plain; charset=windows-1252 > >A choke in the middle of the transmission line could help, but the usual >configuration is a current balun at the antenna to reject common-mode >signals at the source, plus an optional choke at the entrance to the >shack to reject noise picked up by the outside of the coax shield. > >A coiled-coax choke works OK, but you get the best rejection from a >toroid-based choke or balun. I?ve had good results with the ones from >Balun Designs (http://www.balundesigns.com). > >Putting a Balun Designs balun at my dipole dropped the noise by 6dB. > >I highly recommend K9YC?s super-detailed explanation of fighting noise in >your antenna and elsewhere in your shack. > >http://audiosystemsgroup.com/RFI-Ham.pdf > >wunder >K6WRU > > >------------------------------ > >Message: 8 >Date: Mon, 20 Oct 2014 20:31:35 -0700 >From: Jim Brown <[email protected]> >To: [email protected] >Subject: Re: [Elecraft] Coiled Coax Choke >Message-ID: <[email protected]> >Content-Type: text/plain; charset=ISO-8859-1; format=flowed > >On 10/20/2014 7:28 PM, Dauer, Edward wrote: >> I am thinking of adding a coiled coax common-mode choke to my system. > >Although it's all over the literature, a coil of coax is NOT an >effective common mode choke. I've discussed this at length in >k9yc.com/RFI-Ham.pdf > >What do you mean by "antenna/balun?" The word "balun" describes at least >a dozen different things. What problem are you trying to solve? > >73, Jim K9YC > > > >------------------------------ > >Message: 12 >Date: Tue, 21 Oct 2014 08:29:38 -0400 >From: david Moes <[email protected]> >To: [email protected] >Subject: Re: [Elecraft] Coiled Coax Choke >Message-ID: <[email protected]> >Content-Type: text/plain; charset=ISO-8859-1; format=flowed > >You say a 1:1 balun. What type is it and should it not be preventing >common mode currents? If not Id consider one that will rather than >adding a choke. I bought a commercial 1:1 Balun opened it up and found >it to be just a length of RG8X looped once inside the casing with half a >dozen ferrites around it. What I have done is have ground rods at the >base of the pole. I am using a 10-80 +warc fan dipole that looks a >little like a flattened spider web supported with guyed camouflage tent >poles to about 40 ft I have 6 ferrites on the coax at the feed the >ones I got out of the commercial balun. Then at the base I have several >5 ft copper pipes driven into the ground around the pole about 5 ft >apart all bonded together with 6 gauge bare copper that is also burred >a few inched below the surface safe from the lawn mower. I have a >barrel connector at the base that lets me connect the shield to this >ground I have no common mode issues. at least I have not experienced >any. > > ______________________________________________________________ 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]
