I roughly did this test with a USB charger that I am thinking to mount on my wanna-redo-the-panel of my KFIV1050. I used a handheld radio only on 130.000 which is the frequency I use 99% of the time. The noise appears when I take the radio/antenna closer than 20cm (8" circa), and suddenly disappears when I move it away, in any direction. It seems that the charger emits lot of noise but with limited power so that it can't reach too far away.
The question now is whether installing it fairly far away from the radio set and antenna cable would save from interference. Let say finding a spot on the firewall right end giving around 15" of distance from the antenna/radio set, (not on the panel, not easy to reach, but...) would be enough?
In alternative, is there a way to screen the usb as it doesn't send frequencies out?
Or any other trick someone has adopted to make this USB converters work properly (including buying one of a specific brand and doesn't cost a fortune).
As the working alternative is still a good power bank.
P.S. The USB Plug emits noise only when a device is actually connected and charging; if it is just powered but empty, it doesn't radiate. If you tried yours with no device, it doesn't count![]()