I have a USB socket installed in my Td5 Defender where the cigarette socket was. I probably got it off Ebay ... look like these

DS2013 Dual USB Car Charger Socket Waterproof Power Outlet 12V/24V 1.0
– Etronx Australia

It is causing interference with the FM radio ... even with no USB cable plugged in.

Can anyone recommend similar products that don't suffer the same fate? Would prefer something with 2x2.1A ports or better.