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Screeching heterodyning on AM stations on car radios

PForbes

New Member
I have a 2016 Chevrolet Impala whose entertainment centre has a problem on AM radio stations. Periodically, mostly on rainy damp days, a strong heterodyning sound comes over my radio stations sound drowning them out. I experienced the exact same phenomena with my Blaupunkt radios in my Jetta's back in the day. A GM technician suggested that it was the shark fin antenna that was at issue. The Jetta's did not have that. They had a cowl mounted rod has an antenna. And they both had the same issue. Any suggestions, anyone? Sounds to me like an amplifier or preamp as the case may be inside the chain of the AM audio paths doesn't like High humidity. I have a M4A file of the sound but I can't add it here for you.
 

JimB

Super Moderator
Most Helpful Member
I have also experienced screaming noises on AM radios.
The cause has been due to static electric charge in the rain, or often on suitably cold days static charged hail.

When I lived in the Shetland Islands, sevreral times I had to repair my car radio because the static charged hail popped the RF amplifier transistor.


Side note.
When I refer to "static" I mean static electricity, the stuff which eventually makes lightning.
I do NOT mean any random noise on the radio, as per Hollywood, and others who know nothing about radio.
RANTMODE = OFF

JimB
 

PForbes

New Member
I have also experienced screaming noises on AM radios.
The cause has been due to static electric charge in the rain, or often on suitably cold days static charged hail.

When I lived in the Shetland Islands, sevreral times I had to repair my car radio because the static charged hail popped the RF amplifier transistor.


Side note.
When I refer to "static" I mean static electricity, the stuff which eventually makes lightning.
I do NOT mean any random noise on the radio, as per Hollywood, and others who know nothing about radio.
RANTMODE = OFF

JimB
Yes, Jim. I am familiar with that particular type of screaming noise. What I am experiencing is not that. It is as if an amplifier has its class changed and is oscillating.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
It's like vinyl LPs, they're making a strong comeback. If you don't know what a vinyl LP is, google it.
I've still got my vinyl collection and turntable, although I've never used them since they were superseded by the far superior CD :D As for a 'strong' comeback, it's making a very minor comeback - and only with people who were never there originally :D

However, AM radio is so crap, why would it make a comeback?, and why would anyone still be broadcasting it?.
 

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