[Elecraft] Coiled coax choke

[Dauer, Edward]

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
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>Message: 6
>Date: Mon, 20 Oct 2014 19:48:29 -0700
>From: Walter Underwood <wunder at wunderwood.org>
>To: "elecraft at mailman.qth.net" <elecraft at mailman.qth.net>
>Subject: Re: [Elecraft] Coiled Coax Choke
>Message-ID: <B64C9B34-E2D9-489E-8B49-8962F72030DE at wunderwood.org>
>Content-Type: text/plain;	charset=windows-1252
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>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.
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>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).
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>Putting a Balun Designs balun at my dipole dropped the noise by 6dB.
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>I highly recommend K9YC?s super-detailed explanation of fighting noise in
>your antenna and elsewhere in your shack.
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>http://audiosystemsgroup.com/RFI-Ham.pdf
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>wunder
>K6WRU
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>Message: 8
>Date: Mon, 20 Oct 2014 20:31:35 -0700
>From: Jim Brown <jim at audiosystemsgroup.com>
>To: elecraft at mailman.qth.net
>Subject: Re: [Elecraft] Coiled Coax Choke
>Message-ID: <5445D397.9040006 at audiosystemsgroup.com>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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>On 10/20/2014 7:28 PM, Dauer, Edward wrote:
>> I am thinking of adding a coiled coax common-mode choke to my system.
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>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
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>What do you mean by "antenna/balun?" The word "balun" describes at least
>a dozen different things. What problem are you trying to solve?
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>73, Jim K9YC
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>Message: 12
>Date: Tue, 21 Oct 2014 08:29:38 -0400
>From: david Moes <dmoes at nexicom.net>
>To: elecraft at mailman.qth.net
>Subject: Re: [Elecraft] Coiled Coax Choke
>Message-ID: <544651B2.2000805 at nexicom.net>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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>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.
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