cobra ltd29bt/wilson fgt-4

For your first question I have a suspicion that your radio will sound and perform less than optimum with VR4 maxed out. Sorry to be critical but modulation should be set very close to 100% - if without a 'scope then at least with a Modulation meter.

Built-in SWR meters are notoriously inaccurate. I always suspect a flat SWR as a possible problem with even an external meter. I say possible because even though I've never got everything perfect perfection must exist, right?

It sounds like your friend has a problem with his antenna (including placement, mount, etc), coax or radio. I would look for problems in that order.

Ted

 

If it's factory installed coax that could be his problem. The factory will use some of the cheapest coax and connectors found. The Wilson FGT 4 ft antenna, and the Cobra 29 are very good products. And both are know to work very well. The other driver could have a problem with his signal bouncing off the trailer. Because of a higher powered Galaxy, or a poor ground. I would check his ground first.

 

If y'all could get together for an hour or so with both (identical?) trucks it might be interesting to test the antennae and coax by swapping radios - not for a run but just to check the SWRs using each other's radios. Check them with an external meter vs. the meters in your radios too, if possible. If neither of you have one maybe you could borrow one just for the test.

The very best troubleshooting technique is a direct swap with known good components. You would know what your radio would do in his truck and what his radio would do in your truck. It would also give you some confidence in your built-in meters.

The squeal might indicate a mic or speaker placement problem if he uses talkback. I would turn it off.

I think some antennae are more susceptible to grounding problems than others. Some are made for no ground planes at all. Antennae made for boats come to mind.

Ted

 

When the SWR reading is 3.0 or higher, this is usually an indication that most likely there is a ground plane problem or possibly bad coax.
. If you have access to a short length of RG58 or RG8, in the truck with the high SWR, run that coax from the radio directly to the antenna. Recheck the SWR. If the SWR drops, his coax was bad.
.
. If not, he has a ground plane problem. Apparently, not all the large metal parts of the truck are connected together [BONDED] to form a large enough effective RF (radio frequency) ground plane.
. Check the resistance from the antenna mount to the door. It should be zero. If not, run a (perferably flat) ground strap from the antenna mount to the door. Recheck the SWR.
. Check the resistance from the antenna mount to the door frame hinge. This should also be zero. If not, run a ground strap from the door to the top of the door hinge on the door frame side. If the door has two hinges, also run a ground strap on the door frame side of the hinges from the bottom of the top hinge to the top of the lower hinge.
. Recheck his SWR.
. That should solve the problem. If not, run a ground strap from the bottom of the door frame to the chassis ground.
.
NOTE: While you are using a ground strap, this is not electrically grounding. You are BONDING the large metal components to form a large effective RF ground plane. Do NOT use one long ground strap. Short ground straps are the correct procedure because a long ground strap will act as an antenna which you want to avoid at all costs.

 

disregard....

 

i know this is the wrong thread but i have a cobra 29 ltd classic, its my second radio. the only reason i use mine is for plowing parking lots, but lately ive been looking into tuneing it for the max distance. im running that radio with the crappy white whips that are not expensive. i looked into the online manual for the swr setting. i fallowed that it said to do. but i was wondering of you set the switch on cal and keep turning it back so the meeter reads all the way to the left does it make a difference or should i just fallow the directions