How to avoid engine feedback thru PSR500 speaker when connected to car audio input

[prcguy]

The OP would be taking the earphone out of the scanner (low impedance) but feeding a high impedance audio input to the car stereo. That should work fine. The ground loop isolators can be a transformer or a simple capacitor to break the DC path and just let AC audio pass through. The point is to stop the shield of the audio cables from trying to bring the grounds at different points in the car tot the same potential by passing current through the shields.

It's a high impedance galvanic isolated transformer, usually two of them to handle stereo signals. It is not suited for low impedance loudspeakers. It helps with most noise problems from humm and generator whining.

/Ubbe

 

[krokus]

When I used to feed my 500 into my laptop, I would get a loud ground loop hum. Connecting the programming cable would eliminate the hum, by tying the grounds together.