I've been seeing all these articles about the Palomar, Hy-Gain, etc. baluns and
ferrite cores are not good, like they advertise. So who is it that sells these
special "Fair-Rite" cores?
-----Original Message-----
>From: Jim Brown <jim@audiosystemsgroup.com>
>Sent: Feb 15, 2009 8:14 PM
>To: "towertalk@contesting.com" <towertalk@contesting.com>
>Subject: Re: [TowerTalk] To Choke or Not to Choke?
>
>On Sun, 15 Feb 2009 17:58:56 -0800 (PST), Edward Sylvester wrote:
>
>>I have a LW/Inv L that I will feed thru an auto tuner at the base,
>>with radials. Was wondering if I should bother with forming a
>>coaxial choke (12-15 turns at 6" diameter) before it enters the
>>shack 30 feet away.
>
>I coil of coax with no ferrite is a waste of coax -- it will look
>inductive, the rest of the line will look capacitive, and the result
>will be lots of feedline current. You DO want a choke on the coax
>side of the tuner, but it needs to be 7 turns through five Fair-Rite
>#31 1.4-inch i.d. cores (commonly advertised as FT-240-31 by those
>mark them up 4X their cost and resell them to hams). If you're
>feeding with RG8, you will need to wind the choke before you put the
>coax connector on -- you can fit 7 turns through those cores, but
>only with no connector attached.
>
>For a tutorial on all the technical background on this see
>http://audiosystemsgroup.com/RFI-Ham.pdf
>
>73,
>
>Jim Brown K9YC
>
>
>
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