CB Cobra 29 NW LTD Classic

What kind of truck ? I drive a 2020 T680 and when using President Mckinley radio I can hear rpm' s increasing or decreasing, the transmision shifting ( auto pos) its quite annoying, strange though its not that noticable with a Cobra 29, dont know if it has better filtering or less sensitive receive.

 

Remove the antenna and see if you still hear it and try to pinpoint the source, coming throught power cord or antenna.

 

Fuel pumps are first to suspect. Then coil-on-sparkplug ignition.

See the mobile amateur radio bible:

www.k0bg.com

.

 

Correction: The new T680 ( 2020) that I just moved into , the Mckinley is not picking up engine noise like it did in the previous T680( 2019) dont know why but Im glad.

 

Where have you been grounding your cb in the dually

 

Try making a shorter ground to inside of truck. Shorter wire means less RF
Also look up choke insalators.
You may have to install a CPL on your power line going to your battery
If not then it's your alternator . It's a harder thing to ground it.
While your at it go ahead and run a ground to wiper motor. 90% of us who run wipers hear it in the radio when it's raining.
Vehicles in general esp trucks (Chevy) are bad at bieng grounded from the factory. Your truck is your ground plane.
Make sure your ground wire is short on your antenna mount.the longer it is the more it acts as a radial which that's not what you want.you want RF ground

 

That's exactly what you want, you want a balanced antenna.