85 720;Alternator buzz in the radio?? 85

[85 720 king cab 4x2]

Can anyone help me with the buzz in my radio from the alternator goes up with accelerator down with accelerate.I even installed an Insta powered 30 amp filter the buzz is  just as bad if not, worse, could there  be a ground in the radio harness besides the radio ground??any help would be greatly appreciated. 

[datzenmike]

The negative battery cable usually has a bolt through it into the radiator support. Have a look. After almost 40 years the negative cable may have been replaced and the body sheet metal ground left off.

 

May be a fault in the alternator voltage regulator.

 

Does the alternator have a small condenser (capacitor) on the back side of it?

[IZRL]

More than likely there is a ground loop somewhere as Mike explained. I included a video below of things to check to see if you have a ground loop that you can try. If fixing ground connections doesn't help then try what I did below. Mine was not so much a static sound but more of a "whining" alternator sound which also went up and down with vehicle RPMs.

 

I got an alternator "whining" noise when I installed a small amp for my mid-range speakers. I tried most of the tips in the video below and none of them worked (these tips are worth a try in case your noise is caused by ground). I also bought a filter that didn't work.

 

What ended up working for my situation was adding "Ferrite Core" Snap on rings to the +12v (Power wire) of the amp I installed. You want to install the ferrite clamps as close to the stereo/amp as possible. It takes a bit of experimenting to get the best results. It also seems to work best if you wrap the wire multiple times through the ferrite core. Surprisingly enough it also matters how many times you wrap it. For my system I got the best results wrapping it twice. Wrapping it once didn't remove the sound and wrapping it 3 times was less effective than wrapping it only twice. I added a second smaller ferrite core on the wire, but I don't recall if it actually helped or if I just added it for kicks?

 

I also ran all the speaker wires as far away from the power wires as possible. I found through some research that it's best NOT to put ferrite cores on the speaker wires as it might interfere with the speaker sound. The sound didn't go away 100%. I can still hear it if I turn the stereo volume down to zero, but even then I have to really listen closely to hear it. Can't hear it at all even if the music is at lowest setting so it's a win.

 

Here's the link to the snap on ferrite core clips I purchased if you decide to give this a try https://www.amazon.com/dp/B01N0AV746?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

This is what worked with the power wire on my amplifier.

 

 

This is a video of someone fixing CB Radio Static with Ferrite Cores.

 

 

This is what you can use to troubleshoot if you're problem is caused by ground loop.

 

Edited August 5 by IZRL