Ignition noise usually is more of a popping snapping noise. A whining noise is usually the alternator.

And you are not going to measure the whine with a voltmeter on AC. The whine is a very high frequency, the regular meter is not sensitive enough to read it.

If you do a search on the internet, for some reason audio systems seem to get by with the stock noise suppression on the truck, while most cb and ham radios do require the choke be installed to get rid of the noise on them.

 

Ooh, ooh, ooh! How about this? Make sure the battery is fully charged. Put it on a charger overnight if needed. Then remove the drive belt and run the engine briefly. With no alternator rotation, see what happens to the whine.

You may kiss the ring.

I also like the troubleshooting (ground loops, etc.) given in that PDF.

 

With you mentioning that I do have the power wire for the Linear and the CB taped up in a dual wire harness running side by side with the main factory harness on the driverside fender into the cab. I was thinking this morning before I checked on here maybe I should unplug my voltage regulator to deactivate my alternator and see if the whine goes away this would rule out alternator or ignition depending on if the whine stays or goes.

This isn't a pop its a whine like a high pitched hum not a pop or grumble. I think if heard ignition interference before and if I remember right its a high pitch pop in the radio similar to the pop when switching a radio on and off.

Battery is new, I also drove the truck yesterday so what I was thinking this morning was simply unplugging the regulator or the trigger wire on the alternator itself to deactivate the alternator. I would have to first warm the truck up so it wont go on high idle and force the alternator to charge. If the whine is still there then it very well could be on the ignition side. I didn't think about this but my power wires for linear and CB are ran side by side with the factory harness on driverside which also happens to contain the circuit for my factory tach. If I knew which connector was the one to unplug for the tack under the hood I would unplug it and see if it goes away that would at least rule out the tach wiring.

But disconnecting the alternator would do the same thing if I take the alternator out of the picture and the whine is still there then its not the alternator if the whine goes away then it is the alternator. I might also have a faint whine from the tach wires it might be a two fold problem seeing as my AM/FM radio has a faint whine to it as it is but you have to turn the volume off all the way to hear it. On a quiet CB you would probably hear it either way.

I'm thinking seriously of getting something like this.


I found some made by other companies same box just different name on it that actually has the plug terminal already made in. But thing is do I buy two of them and put one on my CB and one on my Linear or just buy one for the CB. After all my Linear and CB are being powered by the same fuse box under the hood and the wires are routed side by side.

 

Be careful and check your power requirements for the linear. You may need to get two of the above noise filters, if they are 120w they only handle 10 amps. It may not handle the cb and the amplifier.

 

They are on two separate circuits. The Linear is fused 10A and the CB circuit is fused 5A.

But I was looking at the truck just now noticed my main power wire for the fuse box I added in was the last wire on the battery side of the solenoid lug. So it was battery cable, alternator charge wire, then fuse box power wire. I flipped it around so the battery cable is between the alternator charge wire and the power wire for my fuse box. The whine is pretty much gone now its still there I can hear it but its not loud enough to be heard over my AM/FM radio.

But now I have a new problem before I did anything I was warming the truck up so I could disconnect the alternator and I noticed when I turned my RF down on my CB and turned my squelch down my antenna is now all of a sudden picking up the ignition on my truck. Its a popping sound at steady intervals that speeds up and slows down with the truck. The few transmissions I received had some static in them and I couldn't hear them because the popping was in the transmission as well. Touching the antenna itself caused the popping noise to go halfways away but it was still there. I just don't know why all of a sudden out of the blue this problem came up. The setup hasn't changed since I had my Cobra 29 radio and it never made this noise. I installed my Galaxy yesterday and never made this noise only the loud high pitch whining. Now today it was whining and popping in the radio. I got the whine resolved for the most part and think I can use a single automotive capacitor at my auxiliary fuse box to remove the last bit of whine but now I have this pop to deal with.

 

My guess would be a phase out of the alternator since you're only charging at 13.3 volts. Try unplugging the regulator and see if the noise stops. If it does the problem is in the charging system, if it doesn't it's in the ignition. Another test would be to measure the voltage on the stator terminal of the alternator and compare it to the output voltage. It should be exactly half.

 

Well I did reduce the noise by a good 75% by just moving wires around on the solenoid so the battery cable is touching my main power wire for my auxiliary fuse box. Last little bit I should be able to filter out by using a noise filter.

Right now I am more concerned with this popping noise my antenna itself is picking up all of a sudden today. If I switch to high side band the meter on the radio just bounces around like crazy for 0 to 10% modulation steadily. In AM mode it doesn't bounce but if you turn RF down enough so you don't have the atmosphereic static and turn squelch down you can hear the popping in the radio.

I guess I could just turn the RF up higher to get more static and just turn my squelch up higher to over compensate for that. But Ive always on my Cobra 29 ran it where squelch is off then turn RF up till you just hear static then turn a little more then move squelch up till static stops then a little more for buffer. Maybe I just need to change how I set up this radio but it doesn't change that I ran high side band yesterday with engine running and it didn't act like this. But I did turn RF down and squelch down but even with RF turned up and squelch turned up I could blank out the popping noise but the needle was still bouncing around like crazy.

 

Convert to diesel. Problem solved.

 

easier said than done. Wonder if anyone ever did a 7.3 conversion on a short wheelbase F150.

In any case this is a problem that just came up and with work being slow I am trying to properly diagnosis this without just blowing more money throwing parts at it. I resolved most of my whine the last bit I will try a capacitor at the fuse box I installed under the hood, I can pick those up fairly cheap from amazon. But now antenna filters I can get but I don't know if that will stop my problem. I'm doing some reading on it but not finding much about antenna interference might need to start doing some reading on antenna filters themselves and what interference they filter out.

 

Run the truck at night with the hood up. Spritz some water on the sparkplug wires. Look for sparks. Any type of miss or bad wire or something wrong under the dist cap will cause more noise in the radio. You may actually find a problem, fix it, and fix the radio problem and a engine problem you did not know you had. Sometimes it's hard to hear a slight miss when you have one acting up out of 8 total.

 

That's what I am starting to wonder about. Truck has ran rough on me twice in the last three weeks or so. First time was a few weeks ago then it faintly did it today. Between this time I could have swore I felt a slight bump in the engine where it felt like a miss but I never noticed the tach drop. Drives fine and doesn't miss under load.

Same thing it was doing with these spark plug wires when I finally changed the set out back in January 2016. I mean that's the only thing that I can think of I replaced the whole ignition system January 2016 trying to find a issue I had then. Truck was just like flipping the key off for a second at highway speeds then back on just a huge drop in RPM from 2500 rpm @ 70 mph down to 1500 rpm before picking back up. I chased my tail then but now I am thinking if I order another set of plug wires and replace it (will check the cap and rotor tomorrow at work but it was new in January 2016) if the popping goes away well then I got a great way of telling when my plug wires are going bad. Just drive till the CB starts to pop through the speaker.