Hi Steve,
     I went to the link you gave and bought a pair of half inch chokes. I 
thought I would snap them on the cable between my power supply and the 
radio. Should I put them next to the radio, the power supply, or one on each 
end of the wire?

God bless,
Mark
-- Currently in Pendleton, Eastern Oregon Regional At Pendleton, Oregon 
Clear, 64.0
----- Original Message ----- 
From: "Steve Forst" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, June 05, 2008 1:05 PM
Subject: Re: correctly using Radio Shack RF chokes


> Hi Tom,
>
> Not wanting to correct the professor, but for what it's worth,  they are 
> not
> magnets, although they  have magnetic properties.  They are made of 
> ferrite,
> which is  a ceramic that has iron mixed in.  As someone said there are
> various "mixes" which  would have  differing properties  suitable for
> different frequencies.  You would need to worry about the different mixes 
> if
> you were building a balun  and needed to cover a particular freq. 
> Shouldn't
> be a big deal when doing rfi stuff.
>
> You are doing it correct.  I don't understand the math behind it, but 
> every
> turn of the wire through the core increases the choking by  the square 
> root
> of something or other, so the more turns the better.
>
> Other (cheaper) sources besides RS are Amidon, and Fair-rite.  Another
> source I've used is:
>
> http://www.allelectronics.com/make-a-store/category/235/Ferrites/1.html
>
> These are slightly different, in that  you open the plastic clamshell and
> lay the wire in like putting a hot dog in a bun and then close the plastic
> shell.   Different sizes for different cables, or use a larger size and 
> wind
> the cable several times.
>
> When running 600 watts on 160 I was getting some  sounds from the internal
> keyer in my headphones, while not using that keyer.   Some trial and error
> and found that clamping  one on the 12 v  line from power supply to rig
> cured it.
>
> 73, good luck Steve KW3A
>
>
>
> ----- Original Message ----- 
> From: "T Behler" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, June 05, 2008 2:07 PM
> Subject: correctly using Radio Shack RF chokes
>
>
>> Hi, all.
>>
>> This is probably self evident, and maybe I've done it the only way
>> possible,
>> but could someone tell me how to most effectively use the rectangular
>> Radio
>> Shack RF chokes for dealing with RFI?
>>
>> I guess I'm asking this question basically because my strategy doesn't
>> seem
>> to get any results whenever I try it.
>>
>> What I do is open the top of the choke, wind the wire through the bottom
>> of
>> the choke, and then close it up again.
>>
>> If there's some other way to use these chokes, please enlighten this
>> sometimes slow learner.  (grinning widely here)
>>
>> If you don't recall what the Radio Shack RF chokes are like, they are
>> rectangular in shape, with magnets on the inside.  You open the latch on
>> the
>> top, and then close it when you're done winding wires around it.
>>
>> Hope this somewhat convoluted e-mail makes sense.
>>
>> 73 from Tom Behler:  KB8TYJ
>>