Steve:

You can correct this tired old professor any time!  (grin)

If I was a professor who knew everything, I'd be making way more money than 
I am now, and probably would be running some d x pedition station from some 
exotic island somewhere.  (grin)

Thanks for the clarification on the cores.

From what I'm gathering on the list, there are several different theories as 
to actually how to wind the wire, so I'll just have to do some trial and 
error here, and see what works.

Thanks as always for your very helpful responses to this question, and the 
various other  questions I've asked over the years.

73 from Tom Behler:  KB8TYJ

----- Original Message ----- 
From: "Steve Forst" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, June 05, 2008 4:05 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
>>
>