Sure sounds like a weird one.
Maybe try a temporary alternative power cord to a different power
source/outlet.
Steve, NA5C
Sent from my mobile device
> On Dec 21, 2025, at 6:14 PM, Dave (NK7Z) <dave@nk7z.net> wrote:
>
> Hello RFI group,
>
> I have an RFI case I am working on right now, that has stumped me
> completely...
>
> A fellow Amateur has an Laing under sink recirculation pump model
> ACT-303-BTW. Every time he transmits, the pump kicks in. The following
> steps have been tried.
>
> 1. A Pile of clamp on ferrites have been added to the short power cord,
> maybe 5 of them. No room yet to wind on an FT250-31, but that may be next.
>
> 2. The water piles have been connected to ground, using a car jumper cable.
> The person who put this on tells me he used the ground on a outlet... Yes,
> we will test differently with a real ground at some point soon.
>
> 3. He has reduced power to 50 watts and the pump still kicks in.
>
> 4. He has wrapped the pump in foil, and grounded the foil. Again, I am sure
> via the outlet ground.
>
> 5. His dipole, which is close to the home, has a quality Balun Design choke
> on it at the feedpoint.
>
> 6. The coax has been rerouted to as far as possible from the device as
> possible, running on the ground as a test.
>
> The device is an older one, and sits under the sink. The ham is not sure if
> his cold water pipes are at actual ground.
>
> I intend to do the following:
>
> 1. Use a real ground, if needed to ground the cold water pipes to the
> service ground then bond to the pipes at the pump.
>
> 2. Replace the power cord with a longer version, and wrap 12 turns of AC
> line cord in an FT240-31, and/or add an external RF filter to the AC line.
>
> 3. Reduce power further to try and pin down where the RF is getting in,
> pipes, or power line by isolation.
>
> Purchase a good RF filter for the AC line. Can someone suggest an OTS one I
> can recommend? He operates 80-10 Meters...
>
> Any other ideas?????
>
> 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:
> We are dominated by the relatively small number of persons who understand the
> mental processes and social patterns of the masses. It is they who pull the
> wires which control the public mind.
> Edward Bernays
>
>
>
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