Topband: Toroidal common mode choke

Jim Brown jim at
Sat Nov 17 14:53:50 EST 2012

On 11/17/2012 11:11 AM, ZR wrote:
> The question was for RG-58. Have you made tests using that and 
> published it?

Yes -- for RG8X, it's in the same pdf.  The difference is stray 
capacitance, and RG58/RG59/RG8X behave similarly, based on conductor 
diameter. There CAN be some differences based on dielectric properties 
outer jacket. That's what makes THHN more broadband than enameled wire.

> Also the difference between Mix 31 and 43 is not great and was used 
> for decades successfully before 31 was introduced.

At 2 MHz, the difference is QUITE substantial, and less so at 3.5 MHz.  
For the rest of HF, they are roughly equivalent, with #43 slightly 
better above 20M Yes, #43 cores can be made to work on 160M, but not 
nearly well for the same number of turns and/or core material.  See the 
measured data in the pdf.

73, Jim K9YC

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