Many small electronic devices have switching regulators in them that can generate a bunch of Radio Frequency Interference (RFI). This is not my first encounter with RFI-spewing devices. See this article about a automotive 12V-to-USB adapter giving me trouble: This Interference Seems To Follow Me Everywhere
I recently bought a couple of adapters that are physically larger than the one I wrote about. I was thinking that a larger size might allow for a little more filtering and a design that does not radiate. I was half right: one of them works pretty well, the other is an RFI Bad Boy.
Take a look at this short video where I check them out.
This is an Amazon link to the adapter that works pretty well.
Enercell® 2-Port USB CLA Car Charger
73, Bob K0NR