Any ideas on this radio issue?

I have a Cobra 148 GTL and have had it for years in various and sundry trucks. In the past couple of months, it has developed a "pulse" when people talk. To better describe the issue, when I have the squelch turned where I can hear some noise, static, etc, when someone talks, you can see the meter go back and forth, left to right and it will continue doing so until the person quits talking. Occasionally, the radio will do this when there is just static noise. It would be easy to say someone nearby is keying and unkeying their microphone, but the problem happens all of the time. Additionally, I have a distance problem. If I cannot see another truck, I cannot hear another truck, even with the squelch all the way to the left and the RF gain all the way to the right.

The antenna set-up is all factory on an 2012 International Prostar. I have a decent antenna set-up at home, when I ever get there, that will be taking the place of the factory stuff. It is Wilson Super Mini 8 silver coax, 4 ft Firestick II antenna and a big gaudy-looking K-40 6-allenscrew antenna mount. I prefer the Firestick brand due to being Made-in-the-USA.

The SWRs on the unreliable radio meter shows 1.30:1.75 from channels 1 thru 40 and it is consistent every time I check them.

Do you think the new antenna set-up will alleviate the pulsing and distance problems or do you think it's time to let a shop check out the radio?

 

Thanks for your input. And yes, everything from the coax to the antenna tip will get replaced.

I also understand inverters left on will make a difference from time to time. I have a small inverter constantly on, keeping power to my laptop but turning the inverter off makes no difference in TX or RX.

If I had a back-up radio, that would help narrow down where the problem is, but I hardly ever use my primary radio, so a back-up would get zero use (except for trouble shooting).

Thanks again.

 

The pulsating is not as bad when the truck is turned off but I hadn't thought about the cell phone chargers. I will try that and see if unplugging them make a difference. That may very well be part of the problem (3 chargers).

 

Here is a little update for anyone interested.

I finally went home and got my new antenna, coax, and mounting bracket. I needed a wrench that was in my truck, so I took my tool bag from the truck to my POV.....and promptly forgot about it when I left, so now I have a complete new set-up in the truck and no wrenches to install them. I will eventually get everything on the same page.

On a side note, I stopped at a recommended CB shop late last week. I described the problems and the gentleman checked out the radio. He found no issues with it (I know, big surprise, but at least that is one area that can be eliminated from the troubleshooting). He asked me what antenna I was using. I told him factory-installed. He mentioned the pulsing problem could be due to the electronics in the truck (inverter/laptop, as has already been mentioned in this thread) OR he said it could be the antenna has a broken wire (not necessarily the coax, but on the antenna itself) and that could be the reason for the pulsating...going down the road, with the movement of the antenna in the wind, if it has a broken wire, the wire is making contact, then loosing contact, then making contact, etc.

While I don't know about the certainty of that, I like the theory. It makes sense to me. That would very well explain why there is much less pulsating when the truck is stopped and account for why I can only hear folks or talk to them if I can see them. It might end up my antenna is the reason for both issues.

Stay tuned.....

 

Just to update, I finally got home, retrieved my tool bag and when I stopped the 1st time after leaving home, I removed the driver's side factory antenna and replaced it with the 5' Firestick II. Had my CB on all day long today, as well as my 400 watt inverter, laptop, refrigerator, and 3 cell phones charging.

It appears the tech at Chucks CB Shop in Holladay, TN was correct. Evidently there was a broken wire inside the antenna. The new antenna made a huge difference. Even though I have a new bracket and coax, to maximize time, as well as continue troubleshooting, I only replaced the antenna. With all the electronics on, there was no pulsing and I could send and receive for miles. It makes me very curious and anxious to see what installing the new coax and real bracket (as opposed to an "in-the-mirror" bracket) will do.

Thank you to all who have offered advice. As it turns out, some of it actually helped solve the problem but I am grateful for all of the suggestions.