[TowerTalk] CM Question

[Jim Brown]

On 10/8/2017 4:05 PM, Carol Richards wrote:
> I am finally getting to clean out my shed with 50+ years of 
> accumulated stuff. To my surprise, I found new in the box, 8,  2.4 
> inch cores that I must have purchased from Amidon, many years ago. 
> According to the spec sheet that was included, they are 43-mix. 
> Furthermore, there was a picture with instructions to wind 3 1/2 turns 
> of RG 213 coax through 2 binocular stacks of 4 cores.
>
>
> What is the prevailing wisdom? Should I do it that way or what?

Hi Carol,

My take on it is in k9yc.com/RFI-Ham.pdf

What you describe would be a pretty effective common mode choke for a 
tri-bander, or other antenna covering 14-28 MHz. It would be 
considerably less effective at lower or higher frequencies. And for use 
below 5 MHz, #31 material is superior.

73, Jim K9YC