Truck radio buzz

You never know where the noise is coming from. I fought mine for a long time and finally someone on the FORD F150 FORUM said to use a bypass capacitor on the fuel sender line. That solved my noise problem being picked up on several frequency bands of my HF Ham Radio install.

All of the other normal bypass places as well as filter transformers etc didn't seem to help on this install... Had the same radio equipment in an older F150 with no interference at all. go figure....

Roy Ken

The noise is actually more of a static.
I think I replaced the alternator couple years ago and I remember noticing the noise about the same time now that I think of it.
We have a couple of shops in the area with life long employees that do electronic installs in vehicles. I will talk with them about the rectifier.

Your problem is being caused by the alternator rectifier bridge in your truck. You need to have a good automotive electrical shop test the alternator and install the appropriate capacitors to stop the interference.

IS it a buzz, or a whine, and does it change frequency with engine speed, or with road slope (Faster going up hill even if engine/land speed the same).

This makes a difference.

There is a book on the topic, I read this a while ago (Like 20-30 years) and refer to it from time to time, but I do not currently have a copy.
http://www.arrl.org/shop/The-ARRL-RFI-Book-3rd-Edition/

If the keyboard did what I told it to,, that's the URL for the book.

NOTE This is aimed at Ham Radio operators who are being accused of causing RFI (As I have recently been but I took the easy way out, quiet hours) but I beleve it has a chapter or two on cars interfering with radios installed in them.. You want to check that out first.

The worst thing you could do is cut the antenna.
Many motors and other components of a vehicle create AM interference. If you really want to eliminate it you have to apply the proper filtering to each and every source. Capacitors are the normal method.

Do not cut your radio antenna. It is of a specific length for your frequencies. I would find a way to insulate it from touching the camper shell.
Hard to tell about the noise....whether coming in though the radio power leads or the antenna. Ferrite beads around those lines might help. I would ask the ford dealer since it is not normal.

This happens when I plug my hand-held CB into my cigarette lighter socket. Is there a fix for this?

Googled AM Radio Buzz Filter
This was a common problem years ago. There was a condenser that you placed across the radio power input but I see they have become more sophisticated. These seem to be inline to the antenna.

The type of sparkplugs used affected the problem as well. The buzz frequency would change with engine RPM. I think that is a thing of the past now.