[TowerTalk] To Choke or Not to Choke?

[Jim Brown]

Read the tutorial. Info in Appendix One. 

73,

Jim K9YC

On Sun, 15 Feb 2009 22:54:50 -0800 (GMT-08:00), 
larryjspammenot at teleport.com wrote:

>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 at audiosystemsgroup.com>
>>Sent: Feb 15, 2009 8:14 PM
>>To: "towertalk at contesting.com" <towertalk at 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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