I have had a issue with S9 Plus noise level on HF the past couple months and finally tracked it down to a neighbor couple doors down who installed some cheap Aiboo LED cabinet lights from China. I asked him to turn off the lights to verify the problem and the noise went away. I like to buy a decent set and give it to him to install instead of his current LED lights. Does anyone have any recommendations of some kitchen cabinet LED lights that does not cause any RF noise. He said he hard wire his current set of lights so I like to get something similar. This is the set he currently has that is causing the problem. https://www.amazon.com/gp/product/B075J92SKF/ref=ox_sc_act_title_1?smid=A1EBPVGNZ14Q0W&psc=1 Steve, N3FWE
If you can hear the interference on an AM (or shortwave if you have one) portable radio, you may be able to identify whether or not it's the switching power supply that makes the noise. [Noise level increases as your portable radio approaches the power supply]. If so all your neighbor has to do is replace the supply with a quieter one. An RF quiet switching power supply of appropriate voltage and capacity should be available from a ham supplier or similar electronic supplier.
There is but one way to insure you get quiet lights- test them. Sometimes manufacturers change circuits, and/or vendors from run to run, so what is quiet today, may be very noisy tomorrow, or vice versa...
Start with replacing the power supply of like capacity. Not sure what you mean by hard-wired because the link you show is clearly Plug-N-Cord connected. Either way, there is a 12-volt power supply.
I just changed out all of our under cabinet lights and used this PS: https://www.amazon.com/gp/product/B07MH15GGY/ref=ppx_yo_dt_b_asin_title_o08_s01?ie=UTF8&psc=1 No noise heard so far.
