Buzzing Noise…..

[Seven-Delta-FortyOne]

I had a Uniden 980ssb in my work truck, a Ram 5500. It finally stopped working, would only turn on whenever it wanted to.

I got a new President McKinley am-fm-ssb unit. I used the same wiring and antenna.

The truck is diesel.

When the truck is running, there is a noticeable and annoying buzz that seems to be coming out of the speaker.

The volume knob does not affect it. Squelch does not change it at all, neither does adjusting rf gain. Adjusting the clarifier does not change pitch at all.

The only thing that changes it, is on deceleration it hoss away completely. When the gas pedal is down, it buzzes. When I decel, it disappears. When I’m stopped at idle, it comes back.

For what it’s worth, the truck is a manual. So each time I come off the gas and depress the clutch to shift, if goes away for a minute.

I’ve tried turning off all auxiliary lighting. I’ve tried turning off the exhaust brake, the stereo, pulling everything out of the 12v auxiliary plugs in the truck.

Might this be an issue with the radio itself? I’ve never had this issue before, I’ve had many cbs in many different rigs.

I might try putting it into my dump truck temporarily to see if it’s vehicle or radio.

 

[Trucker700]

Fuel pump is likely the culprit. But, to be on the safe side, I would try the radio in a different vehicle to make sure the problem is not the radio itself.
James

 

[Seven-Delta-FortyOne]

So some units are just sensitive to it, some aren’t?

I would try a ferrite choke, but I wouldn’t even know where to begin with selecting one.

 

[mmckenna]

There are a lot of electronic noisemakers in modern vehicles. Avoiding them can be a real challenge.

A few things to pay attention to (not an exhaustive list):
-Make sure the radio positive power lead goes to the battery positive terminal. Do not tap into existing wiring, cigarette lighter sockets, fuse taps, or other janky short cuts.
-Radio power negative lead should be grounded to the body sheet metal close to the radio. Do not run it all the way back to the battery.
-Make sure all wiring is run in a separate path from existing vehicle wiring where ever possible.
-Same with the coax, keep it away from vehicle wiring as much as possible.
-Don't mount the antenna on the fender next to the engine compartment if at all possible.

Noise sounds engine related, so pay attention to wiring under the hood.

 

[Seven-Delta-FortyOne]

I installed a terminal block under the hood, with separate fused connections.

I ran one + and - into the cab from that for radios. I’ll try pulling the negative off the terminal block and see if that helps.

Funny I never had issues with the Uniden in the exact same setup.

 

[mmckenna]

I installed a terminal block under the hood, with separate fused connections.

OK, good deal.

I ran one + and - into the cab from that for radios. I’ll try pulling the negative off the terminal block and see if that helps.

Not only pull it off, but ground the radio power lead to sheet metal in the cab, keep the negative wire as short as reasonably possible. You don't want the long ground wire acting like an antenna picking up all that stray RF.

Funny I never had issues with the Uniden in the exact same setup.

May be an issue with that radio, its mic. or similar.


A few other things you can try:

Power the radio directly off a separate battery to rule out noise getting in via the power lead.

Remove the antenna plug from the back to see if the noise is coming in from the antenna.

Power the radio up on the bench and see how it does.

Isolating things one at a time will narrow down where the issue is coming from.

 

[Seven-Delta-FortyOne]

Great advice. Thanks @mmckenna !!

 

[RFI-EMI-GUY]

The fact that your first radio, a fairly new one went bad, leads me to suspect that the electrical system is getting spikes of voltage. Do as MmcKenna suggests, especially the radio being grounded directly to the chassis instead of battery as a priority (1). Then I would look at the fuel system (Fuel pump electronic injectors) as cause for spikes if the problem is related to the throttle pedal position rather than engine RPM (alternator).

(1) don't disconnect the radio ground while power is live. Pull the fuse on the positive side first.

 

[slowmover]

OP, I agree with your trying it in the dump truck. Some radios are just more sensitive.

As well as what else is suggested above.

Ignition Notes on RFI

Bonding

Let me also recommend consideration of the post-2022 integrated-NRC radios such as the RadiOddity QT60 as the DSP filter makes it MUCH easier on a crowded channel to distinguish who’s who.

A McK is nice, granted. So are others. But without DSP they’ve been left behind.

2023 Best Mobile CB

Via mobile experience as an OTR truck driver. Several thousand hours annual use. Earlier references to the Qixiang factory’s new circuit board elsewhere. Several brands. The above possibly the best known example at present. Paired with the equally new Driver Extreme DRX-9010 External Speaker...

forums.radioreference.com

As one who has AM-19 on 10-12/hrs or more, daily, the job of monitoring is now far easier than before. More pleasurable, as well.

.

 

[Seven-Delta-FortyOne]

OP, I agree with your trying it in the dump truck. Some radios are just more sensitive.

As well as what else is suggested above.

Ignition Notes on RFI

Bonding

Let me also recommend consideration of the post-2022 integrated-NRC radios such as the RadiOddity QT60 as the DSP filter makes it MUCH easier on a crowded channel to distinguish who’s who.

A McK is nice, granted. So are others. But without DSP they’ve been left behind.

2023 Best Mobile CB

Via mobile experience as an OTR truck driver. Several thousand hours annual use. Earlier references to the Qixiang factory’s new circuit board elsewhere. Several brands. The above possibly the best known example at present. Paired with the equally new Driver Extreme DRX-9010 External Speaker...

forums.radioreference.com

As one who has AM-19 on 10-12/hrs or more, daily, the job of monitoring is now far easier than before. More pleasurable, as well.

.

Doesn’t appear that Anytone has the CB channels.

 

[Trucker700]

They do. But, have to be modified to use them.
James

Expanding the frequencies. AT-5555 Plus. You don’t need the program or a cable to get this on to 27mhz. Just hold Func and EMG in and turn on the radio then let the buttons go. It will be in Band 1; rotate the channel selector one click and it will go to Band 2. Press and hold func till it shows Rend on the screen. Turn the radio off. When you turn it on again it will be in the expanded mode and have 6 bands of 40ch from 25.615 through 28.305. If you want to work 10m you will need to reverse the process and revert to band 1.

 

[slowmover]

The Q5 N2 is the current version.