Heated Rear Window Interferes with Car Radio

Hello,
'I've recently been experiencing the problem described above. Without the heater running, the radio reception is also sometimes very poor. I suspect the antenna amplifier has failed - is there a hidden fuse for it somewhere? (Passat wagon, 1998).'

How do the disturbances manifest? (e.g., weak signal, noise, crackling, or...)

It could be a poor connection in the rear window defroster circuit (intermittent high resistance with relatively high current demand), such as a broken wire, especially near the hinge of the tailgate, or corroded connectors, or a faulty switch (less likely).

Hi,

In original radios, the antenna amplifier is powered via a so-called "phantom power" supply, which is transmitted through the antenna cable. The only protection for this voltage is a current-limiting resistor located within the radio.

I don't know what to do anymore.
How can the poor radio reception be explained (i.e., such strong interference that nothing is understandable)?
The rear window defroster is working, but it's extremely annoying.

Hello!

I heard about this problem from an Audi mechanic (I think it was in NU ), when a heating wire in the rear window defroster is defective! How applicable this is to your Passat: I have no idea?!?

I'm not entirely sure if this only applied to Audi models that had the antenna integrated into the windshield.

Is it possible that a heating element is broken?

Best regards,
Mathias.

Hi Edgar,

What does 'stört' mean? Is it a scratching or whistling sound? Is the frequency dependent on the engine speed?

Indeed, a heating element is broken, but I have a roof antenna...

Hello,

Even the smallest spark discharge generates a broadband interference signal that extends into the FM radio frequency range. In the early days of "radio transmission," spark transmitters were used.

The malfunction can be caused by a defective heating element, a faulty relay, or a loose connection that is causing interference (which is less common, as these connections usually weld themselves shut).
originate.

Best regards,
Christian.