Hi Jim,
Looking at your published plots, it looks like there would not be much
difference on 10 meters between #43 and #31 material for the common mode
choke. Do you agree?
Don (wd8dsb)
On Wed, Sep 29, 2021 at 7:54 PM Don Kirk <wd8dsb@gmail.com> wrote:
> Hi Jim,
>
> I forgot to answer your question about what bands the RFI was on. Mike
> was only experiencing noise on 10 meters, so I did not look at other
> bands. Because we were dealing with 10 meters I also wondered if we should
> try #43 material in place of the #31 material on the common mode choke to
> see if that would be beneficial, and you might share your thoughts on the
> use of #43 material versus #31 material up on 10 meters for the common mode
> choke.
>
> Thanks,
> Don (wd8dsb)
>
> On Wed, Sep 29, 2021 at 7:41 PM Don Kirk <wd8dsb@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@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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>>
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