[RFI] RFI LG Refrig Corcom filter and #31 core

[Jim Brown]

Thanks Don. How is the Corcom installed?  For it to work well, it needs 
a VERY short bond to the chassis of the fridge. I would put the choke on 
the line side of the filter.

On what bands was there noise?

About the choke -- in doing the lab work for the 2018 Cookbook, I 
learned that turns wound around the core that are out of order within 
can cancel, reducing the effectiveness of the choke. Winding in order is 
relatively easy with toroids, but can be very tricky with clamp-ons.

73, Jim

On 9/29/2021 1:32 PM, Don Kirk wrote:
> Hi Jim,
> 
> Once again the toroid core choke did not eliminate the RFI on its own.  
> We tried the K9YC toroid choke by itself and it did not eliminate the 
> RFI, we tried the corcom filter by itself and it did not eliminate the 
> RFI.  It was only when we used both filters in series that Mike reported 
> the RFI was gone.  I also tried the toroid choke before and then after 
> the corcom filter with identical results on Mike’s RFI.
> 
> This is not the first time that I have had to use both filters to 
> eliminate RFI.  The first time was on my wife’s treadmill.  It really is 
> an interesting phenomena.  I suspect we would notice some components of 
> the RFI disappear if looking at it with my SDR receiver or spectrum 
> analyzer when using each filter on its own, but the bottom line is that 
> both filters were required for Mike ti noice the RFI disappear.
> 
> Just FYI,
> 
> Don wd8dsb
> 
> On Wed, Sep 29, 2021 at 3:50 PM Jim Brown <jim at audiosystemsgroup.com 
> <mailto:jim at audiosystemsgroup.com>> wrote:
> 
>     On 9/29/2021 12:10 PM, Mike Wetzel wrote:
>      > My neighbor's LG refrigerator is radiating RFI on 28MHz and Don
>     (WD8DSB)
>      > temporarily hooked up a Corcom filter and a cord wrapped around a #31
>      > torroid core that eliminated the interference.
> 
>     I'd bet that the turns around the toroid were doing all the work. Noise
>     is most often on the green wire, which is a chassis-to=chassis
>     connection on the filter.
> 
>     73, Jim K9YC
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