Cell phone chargers usually use little switch mode power supplies to
convert the car's 12VDC to whatever the phone wants. These SM supplies
can generate a lot of radio frequency interference.  In the case of FM,
a loud signal causes the internal circuitry to reduce volume level, and
it might be blanketing the signal you want to hear.

Your radio is either receiving this interference through the antenna, or
through its 12V power supply wire.

If the former, there is little you can do except try to find a quieter
charger. If the latter, then your car audio shops might have
interference filters you can install on the 12V supply wire to the
radio, and to the cigarette lighter socket. Come to think of it, if wire
going from the charger to the cell phone is acting as an antenna for the
noise, the boys at your car audio shop might have some kind of clamp-on
filter you can wrap around the charger cable at the plug end to block
from going down the cable and radiating all over the place. I'd go talk
to those boys.

--

Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
Carlsbad, CA
KG6RCR

On 6/20/2005 6:53 AM Brian Wasson wrote:

>OK, here's a problem I can't figure out in my 1988 Westy: When plugging something like a cell phone charger into the dashboard 12v outlet (cigarette lighter), the radio sound cuts out (or diminishes so much that you can't hear it). The stereo itself continues to operate fine, and all functions (LCD, etc.) work.
>
>I assume the cig. lighter socket is bad and needs to be replaced, and I will do so (is it necessary to get a direct replacement, or will an aftermarket outlet from Radio Shack or Wal-Mart work). However, I can't figure out why the stereo's sound would be affected, but nothing else?
>
>The stereo, lighter socket, lights, etc. (everything on that circuit) are wired to the aux battery.
>
>Brian W.
>
>
>