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

Wed Oct 13 14:43:43 EDT 2021

If it ever becomes a problem, again, 43 material would better serve
10-meters than 31 material.  The difference is small, but if needed, it
could be useful.

Dave - WØLEV

On Wed, Oct 13, 2021 at 6:34 PM D C _Mac_ Macdonald <k2gkk at hotmail.com>
wrote:

> What "power cord?"  Every APC C2 I found with
> Google is mounted ON the AC wall outlet.
>
> 73 - Mac, K2GKK/5
> Since 30 Nov 1953
> Oklahoma City, OK
> USAF (Retired) 61-81
> FAA (Retired) 94-10
>
> ________________________________
> From: RFI <rfi-bounces+k2gkk=hotmail.com at contesting.com> on behalf of Don
> Kirk <wd8dsb at gmail.com>
> Sent: Tuesday, October 12, 2021 19:02
> To: RFI <rfi at contesting.com>
> Subject: Re: [RFI] RFI LG Refrig Corcom filter and #31 core
>
> Here is a quick followup regarding the RFI at W9RE on 10 meters that we
> tracked down to his neighbors refrigerator a few weeks ago.  We previously
> were able to eliminate the RFI using a commercial power line filter in line
> with a choke based on Jims (K9YC) design in which 12 turns of the power
> cord were wound on an FT240-31 toroid core.  While this combination worked,
> we were looking for a plug and play commercial power line filter to replace
> the Delta Electronics or Corcom filters that worked but were not plug and
> play (they did not have built in outlet receptacles, etc.).
>
> Mike purchased an APC C2 power line filter that had 2 built in outlets as
> well as built in RFI/EMI filtering with a spec of 50dB from 100 kHz to 10
> MHz (can't find the specs above 10 MHz or detailed specs regarding
> differential mode versus common mode suppression).
>
> Mike then wound 4 turns of the APC C2 power cord on an FT240-31 toroid core
> based on recommendations from Jim (K9YC) for use on 10 meters.
>
> Mike then gave the APC C2 filter with toroid core on the power cord as
> mentioned above to his neighbor, and today Mikes neighbor tested this new
> filter combination on his refrigerator while Mike listened to 10 meters
> from his shack, and the new filter combination successfully eliminates the
> RFI on 10 meters that Mike was encountering from his neighbors
> refrigerator.
>
> The APC C2 filter is built like a tank (weighs approximately 2 pounds), and
> we have no idea what the filter circuit inside it really is, but we are
> satisfied with the results and the neighbor appears happy using this plug
> and play system.
>
> Just FYI,
> Don (wd8dsb)
>
> On Wed, Sep 29, 2021 at 7:41 PM Don Kirk <wd8dsb at gmail.com> wrote:
>
> > Hi Jim,
> >
> > For the records, we actually tried two different commercial filters on
> the
> > fridge along with the common mode choke.  Both required the common mode
> > choke in line with it to successfully eliminate the RFI at Mikes, and as
> > mentioned the common mode choke alone was not adequate.  My common mode
> > choke used the FT240-31 core with 14 turns and the turns are tightly
> wound
> > one next to the other in proper order.
> >
> > The case of the commercial filters were not mounted directly to the case
> > of the fridge, but the ground wire from the fridge power cord was
> connected
> > to the case of the commercial line filter, and the case of the commercial
> > filter then had a wire connected to it going out toward the wall outlet
> > ground via the power cord, so the ground wire from the fridge was a
> > continuous connection to the commercial filter case and then from the
> > commercial filter case to toward outlet ground.  All power cords used
> were
> > 3 wire (line, neutral, and ground).
> >
> > The two commercial filters we tried were the Delta Electronics model
> > 20DRGG5 (which is mine) and an old Corcom filter F2212 (which is Mikes,
> and
> > I can't find any documentation on the F2212 filter).  We pretty much had
> > identical results regardless of which one of the 2 commercial filters we
> > used in conjunction with or without the FT-240-31 choke.  Commercial
> filter
> > alone was not adequate, FT-240-31 common mode choke alone was not
> adequate,
> > but both in series work great.  This is the same situation with my
> > treadmill, and I also don't have the case of the commercial filter
> mounted
> > to the case of the treadmill.  Mounting filter case to the case/frame of
> a
> > homeowners device starts getting very intrusive, and I won't take on that
> > responsibility/liability.  As Mike mentioned we need to find something
> > already packaged with incoming and outgoing outlets/power cords for use
> in
> > someones home in order to avoid liability issues.
> >
> > Just FYI, and 73.
> > Don (wd8dsb)
> >
> > On Wed, Sep 29, 2021 at 6:24 PM Jim Brown <jim at audiosystemsgroup.com>
> > wrote:
> >
> >> 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
> >> >     _______________________________________________
> >> >     RFI mailing list
> >> >     RFI at contesting.com <mailto:RFI at contesting.com>
> >> >
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-- 
*Dave - WØLEV*
*Just Let Darwin Work*