That's not surprising. My installer told me that Ecobee. I think, provided
a ferrite bead with their thermostat.
73, Dan
On Wed, Jan 7, 2026, 11:39 AM Alan Higbie <alan.higbie@gmail.com> wrote:
> Dan ~
>
> Often an RFI problem is a 2-way street:
>
> - *Inbound to the device*: the device is susceptible to receiving and
> being affected by RF energy, and also
> - *Outbound from the device*: the device may also radiate RFI out onto
> the HF spectrum.
>
> I had a similar HVAC situation as you describe.
>
> My chief complaint was the outbound RFI from the device - and a raised
> noise floor on HF. But, I noticed transmitted RF (especially at HP)
> getting into the furnace controller.
>
> While, you are on a path to solving your inbound problem . .* it would be
> interesting to see what that device is radiating out*. Sniffing around the
> device with a portable receiver (or SDR) may be enlightening.
>
> Measuring the signal strength of the radiation before and after
> installation of the ferrite (at both ends of the control line) would help
> confirm your fix.
>
> In my case, such measurements after the showed substantial (but not
> complete) reduction in outbound RFI. Then, after the first round of
> ferrite, I added more - and confirmed by measurements that it was done.
>
> *Link to report of my case*:
> http://lists.contesting.com/archives//html/RFI/2021-11/msg00024.html
>
> 73,
>
> ~ Alan K0AV
>
>
> On Wed, Jan 7, 2026 at 7:32 AM Dave (NK7Z) <dave@nk7z.net> wrote:
>
> > Dan,
> >
> > I should have mentioned Jim's site, I consider Jim's site the Gold
> > Standard for ferrite use information, and testing...
> >
> >
> > 73, and thanks,
> > Dave (NK7Z)
> > https://www.nk7z.net
> > ARRL Volunteer Examiner
> > ARRL Technical Specialist, RFI
> > ARRL Asst. Director, NW Division, Technical Resources
> >
> > Random Quote of the day:
> > Did you hear about the physicist who got chilled to absolute zero? They
> > are 0k now
> >
> > On 1/6/26 22:15, Jim Brown wrote:
> > > On 1/6/2026 6:39 PM, Dave (NK7Z) wrote:
> > >> If it were me, and I had that problem, I'd get some FT-240-31 ferrite
> > >> cores from Arrow, or one of the parts houses. I have some of core
> > >> part numbers, and where to find them at web site:
> > >>
> > >> https://www.nk7z.net/rfi-now-house-cleaning/
> > >>
> > >> The ferrite part numbers are listed there, about half way down the
> > >> page, with links to the manufactures site.
> > >
> > > Hi Dan,
> > >
> > > You didn't say what bands were a problem, but yes, some of the wiring
> > > connected to the electronics controlling the furnace is functioning as
> a
> > > long wire receiving antenna, and the solution is multiple turns through
> > > a #31 Fair-Rite core. I try to solve problems like this with clamp-on
> > > cores just large enough to wind 4-5 turns through them, ideally without
> > > breaking existing wiring. I don't see the need go inside any of the
> > > hardware, but you do want the choke (the windings on the ferrite) as
> > > close as possible to the victim.
> > >
> > > I keep three sizes of clamp-ons in my stash for this use. 1/2-in,
> > > 3/4-in, and 1-in i.d. The same cores are useful for killing noise
> > > generated by the dozens of switch-mode power supplies that are in all
> of
> > > our homes, so I suggest that you buy a bunch of the two smaller sizes,
> > > at least enough to get the first price break and to get you free
> > shipping.
> > >
> > > There's tutorial material on my website about how to look for noise in
> > > our homes and in the homes of our neighbors (if they will let us). And
> I
> > > also like Arrow as a source.
> > >
> > > 73, Jim K9YC
> > >
> > > _______________________________________________
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> > > RFI@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/rfi
> >
> >
> > _______________________________________________
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> >
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