I'm trying to use the N900 FM Transmitter in my car.

It seems it's emitting a periodic beep every 5 seconds or 10 seconds or so... Otherwise the signal is good, but the beep is annoying...

If I use an external transmitter plugged into the earjack on the same frequency, no beep is heard, so it's no external beep.

Anyone know what this could be? Or is it maybe that the signal IS too weak and the beep is from the car's audio system signalling its weakness, while with the external FM transmitter the signal is stronger?