ant. light coming on when i key the mic cobra 29 ltd volvo t660

Swifty,
You've listed a lot of information for us, but there isn't really enough in the way of specifics for us to start to diagnose what's going on. Your one-year-old CB -- what is it, and has anyone been inside to do a "tweak and peak" or do some sort of truck stop radio shop magic? If so, and if it's done wrong (not limited to truck stop shops, BTW) that alone can cause the AWI light to come on. If your model Volvo is one of the ones that has a coupler behind the instrument panel (sorry, I'm not familiar with your specific model) so that your CB, TV, AM/FM good times radio, XM/Sirius, and GPS all run off of two small antennas, most of those seem to be about as good for transmitting on CB as a dummy load that's buried 12 feet underground. Receiving isn't nearly as picky about antennas; you can just about receive radio signals with anything from a bedspring to a piece of string that's been soaked in salt water and streamed behind you on a kite.
A quick test to see if it's your radio or your antenna system that's at fault is to borrow a dummy load and screw it onto the rear of your radio. Key the transmitter, check the SWR (should be 1.0:1), power should be up around the top of the scale, and the AWI (antenna warning indicator) should not come on, even a little, even when you speak loudly into the mic. If it does, then your radio has been....ummm..... adjusted out-of-spec so that it's either putting out too much power, or grossly overmodulating.
I think you'll find most folks who have trucks that have the multiplexor style antenna systems that try to do everything with just two antennas and a rat's nest of couplers and jumpers behind the dashboard have opted to run a separate, dedicated piece of coax to a separate, dedicated CB antenna on its own mount, up as high as they can practically get it, with the mount bonded to a substantial mass of metal in the upper part of the cab.
Hope that helps some. Lotsa folks on this forum have had problems similar to the one you've described. If you're able to supply a few more details about your radio, there's probably a handful of people who've solved the precise problem you present.
With hopes for a successful resolution,
73,
Handlebar
p.s. Oops, I just re-read the title on your post, where you clearly stated that you've got a Cobra 29. Sorry about that.

 

It is coming on because the Coax is more then likely cracked and broken at the doors. Another possibility is a bad multiplexor box. Volvos use the same antennas for the AM/FM radio and the CB and the coax runs through that multiplexor box then splits off to to the CB and AM/FM radio.

 

Sounds likely I have fixed several of those splitters. Someone drives the truck running a 4600 Turbo doing 150 watts or a CB/amp combo, and blows open a cheap 50 volt disc ceramic capacitor inside the splitter creating open circuit city. Or the factory antenna has lost the bonding between the ferrel and the fiberglass rod. This allows the rod to move around in the wind until it breaks the copper wire where it is soldered to the ferrel (threaded base). Typically within 8 months the Volvo stock antennas fail in this way. Stick a CB 25 Francis on there and if that does not cure it it could be the splitter. The coax does not fail in the Volvo as quickly as you might think, possible but it is well protected from wind and weather exposure. If the splitter has been blown open you can clip the coax going to one side, and the CB. Install PL connectors and join with a female barrel. The AM/FM will still run off the antenna on the other side, the blown capacitor will have no effect on this. If not odds are the other stock antenna has also failed as described in this post. Usually you will see a crack around the antenna near the base in the shrink wrap covering, it is the motion of the rod within the base which causes this and the broken wire. In the early models the splitter hung upside down just inside the bottom panel which your right knee is closest to while driving. Just a few Tor-X screws hold it on. Easy quick repair plus your then just a 50 ohm coax running to one side direct from the CB. This does not alter the fact that as mentioned above the SWR warning may not have been adjusted for the higher power level after a tune job, common mistake actually. If you can hear several miles this is even more likely, that is the light is going off long before 3:1 is reached.

 

yet one more reason not to use factory installed cb accessories unless you have no choice.

 

It is an easy fix actually. Depending on the year of truck, it is real easy to route a new single coax to the factory mount in the mirror. My old volvo, you could remove all the plastic covers on the mirror and the mirror arms which meant not having to fish the coax through tubing etc. Then rout it under the dash and up through the dash to the CB. Leave the other antenna in place so that you still have AM/FM reception.

We have a ton of Volvos in our fleet and they are all messed up when it comes to CB performance. Everyone I have checked out, you can see the cracked and broken coax were it comes out of the cab at the door.

As far as the failed antennas, yeap I have seen many of them. Copper wire broken off the base of the antenna. I have even repaired them using some silver solder, a map/oxy torch and some shrink wrap. I bend the copper wire down along side the the base then resolder it back on so that it does not break off again. I have even had to do this to Wilson fiberglass antennas and Firesticks. The Firesticks are not that much of a problem since they are alot stiffer then the other antennas.

 

I have fixed many the same way when a driver was desperate to have the CB working but low on money at that time. It is only a temporary fix though. The problem occurs because the fiberglass rod is able to move in the ferrel. They are bonded using therm o-setting epoxy with heat and pressure. In the last decade I have seen large numbers of them made (bonded) very poorly from several brand names. This was a huge problem for Francis around 2005. Being bought out the new owner farmed out the manufacturing to a cut rate company in Asia. I had people coming in within two weeks after buying a brand new Francis complaining they suddenly had no distance. You could tap the antenna against a table and hear a rattle, the bonding was so loose. After 3 or 4 came in like this I tried a dozen new CB25 and 26 models and they would rattle right out of the package. In the Francis case the wires come out the bottom and are soldered at the base. I say wires because if you study the 1970 and 1974 patents you will find three unequal length wires was their secret to being broader in BW. In any case near zero motion breaks the wires whereas in the Firestick design the rod can move for a while before the copper fatigues and breaks. My point is you can resolder the wire but the bonding is still bad allowing the rod to shift in the wind, meaning this kind of fix is like fix-a-flat in a can, just a temporary repair as the continued motion will break it again before long.

 

As handlebar is saying ,you don't have enough information about how your radio is connected? first ,I would check to make sure your antennas are connected to the coax. sometimes when someone is changing that type antenna the coax could slip into its mount and you would never know if its connected.If they are connected then your problem is only partially solved.What I would do is go out and buy a good antenna with an adjustable tip for tuning , new coax 18 feet long,new mount to hold the antenna. Get yourself a $ 30.00 SWR meter and set your match to as close to 1.5:1 as you canbut remember anything under 2.0 is ok and 3.0 is bad

 

A good step to take is to stop relying on people who more than likely aren't FCC Certified Radio Techs on these sites whereas you'll get dozens of answers but not a single correct answer. These people can waste your time and at times waste your money by having you to adjust this or that and now there's smoke everywhere.

Instead try doing things the old school way and getting some books which are written by professionals. Even the Military has extremely well written Radio and Antenna books.

Most people don't realize that the National Average IQ plummets when more and more people rely on others instead of learning things yourself. Hell people used to be able to repair anything around the house but nowadays most people can't even fix a simple lamp.

I guarantee these people here got all their info on the internet which makes them no more knowledgeable than the person asking the question which is why there's always dozens of answers.

Just learn how to install your own system with coax, antenna, and radio. You'd be amazed at how simple all this really is. And yes all this can easily be done with a company truck without drilling a single hole as a temporary install. It can take as little as 5 minutes to uninstall and maybe 10 minutes to install a CB Radio setup. All it takes is reading what actual professional wrote in textbooks.