For reasons I can't figure out my Calibration, SWR & S/RF will not hold steady. It will work fine for a while then I notice no ones talking so I key up the mike and no needle swing & no comeback when I ask for a radio check.

I have tried to recalibrate but most of the time can't get near that mark on the scale. Turning it off for about 5 min seems to help, but I can get back in the truck after my 34 hrs are up and have the same problem. I have replaced coax, antenna, and mount

I know I need to take it to the shop but that will not happen for at least a week or 2.

Appriciate any suggestions.

Thanks, Dan

 

The only suggestion I have is to make sure none of your connections have vibrated loose. Check your mic and both ends of the coax. Also make sure your ant. is tight in the bracket.

 

? Is the radio in question a Cobra 148GTL? I have a 148 that does the same as you descibe, it has a bad solder connection in the PLL. Since I have no need for the radio at this time, I have not invested the time or effort to fix it. This is a common problem with Malaysian made Cobra 148GTL's, have not found the problem in other models.

If your radio is not a 148, check the insulator between the antenna mount and the bracket that attaches it to the mirror. Sometimes these wear out, and ground the antenna. When that occurs, most modern radios have a feature that will kill the power in the radio to prevent frying it. Also check the routing of the coax and connections on both ends, they may be loose.

 

Everything mentioned is tight, & all are new. Wondering if it is an electrical problem, antenna not grounded or power wires.

Thanks for the idea,
Dan

 

It's not a 148 but it is a Cobra 25. What the heck is a "PLL"

Antenna, mount & insulator, and coax is all new and tight. The coax is run between the door & door frame but the problem exists w/ new coax run out the window w/ no bend or kinks in it. Ran it for 2 months w/ the coax between the door & door frame w/ no problems.

Thanks for the suggestions,
Dan

 

PLL is a Phase Lock Loop. The PLL is how the radio determine what frequency to transmit and receive on when you select a certain channel. If it does not lock up then there will not be an output. This is an internal circuit which a technician will have to service.

As to your problem. It would appear you have an intermittent problem. From what you have described it would appear you have checked everything you can check. Your next decision is if you want to get this radio repaired or buy another radio.

kc0iv

 

Ok, so I just dropped my new Cobra 29LTD in my '97 Kenworth and added a 3' Firestick antenna with new coax. Problem is.... I can't get NOTHING??? Everytime I key I can see it, but thats about it??? NO talking, NO response, NO NOTHING... :cry: WTF???

Oh, and is there a special way to have all those knobs set on the front??? I don't remember what all they are, but if anyone knows what they man and what they do.... PLEASE post up!!! (I can't find the manual anywhere!!!)

 

Turn the squelch counter-clockwise, and the RF Gain clockwise. Try that and see if it works.

 

You can download the manual at:

http://www.cobra.com/pdf/CBs/29LTDST.pdf
http://www.cbtricks.com/radios/cobra...29wx-st_om.pdf

kc0iv