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@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@audiosystemsgroup.com
> > <mailto:jim@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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> >
>
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