Disrupts Extem radio reception

In our car (a older Chrysler Voyager) could be the adapter with some trouble squeezing into the cigarette lighter Buxe and then did his service on the iPhone. But listening to the radio is impossible while using the adapter. It rustles and scratching on all channels.
For us, unfortunately a no go, so we will send the charger back.

Now we are faced with the question of which (authorized) Adapter alternatively comes into question. Unauthorized we have two through and above next to the eternal bleating of the iPhone, the problem is that this upload is not reliable.
That you have to invest so much time and energy in something of secondary importance ... sigh ;-)