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
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|