SOURCE: Cobra 148 gtl Low / No receive audio
check/replace the resistor that you can jump with your finger. I did the same on a resistor right beside the ta7222 whutever ic and got my receive back, I am sending out weak sound, but not enough to register anything on my tester yet. looking into my final transistor now and other ideas would be appreciated
SOURCE: Cobra 2000 gtl
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i have yhe same problem
i have clear the contacts on ptt switch and the all contacts in the volume potentiometer
SOURCE: Cobra 1000 GTL by Dynascan
This is a complicated modification. I have never done it to a 1000 GTL, but its done basically the same in all radio's.
I don't recommend doing it, especially since I am not 100% sure on how exactly to do it. I have never been in a 1000 gtl. If I had one in front of me I could tell you for sure how to do it.
If the reason for Variable power is a linear, just a swing kit in for the dead key you need, most likely 2 watts, and leave it.
Here is how to do a variable power mod. this is assuming the swing mod is done the same to this as a cobra 25/29 or uniden 68/76 etc.
If you would like to try it, here it is.
You get a TIP31 transistor, Radioshack has them.
Where you put the swing mod in the radio, which is a cap and a resistor, you put the TIP31 and cap. A 47uf cap works fine.
With the resistor facing you, and the tab in the back away, solder the cap to the transistor. the leg with the black stripe goes on the right most leg. then the other goes to the center leg of the transistor.
Solder a wire on the left most leg, long enough to reach the front of the radio. Now solder the 2 legs that don't have the wire on it, in the place where you would put the swing kit, with the black stripe on the cap facing the back of the radio usually.
Remove the wires from the RF gain and solder them together.
Now solder the wire from the transistor to the center tab.
Remove VR6 and solder a wire from the top tag of the RF gain to the top connection of VR6 that you removed.
Then connect a wire from the bottom tag to a ground point. The side of a tuning can works fine.
Take a piece of shrink tube and put it over the TIP31 so it does not ground against the heat sink, that would be bad.
This is done basically the same in all cb radio's.
SOURCE: Cobra 29LTD CHROME low tx no mod, rx good low Vol, talkback good
1 why would you change the finals?? Have you checked you antenna? How are your SWR's? Crappy antenna's cause a lot of problems.
Use an external meter to see what the SWR is, and see what the output is PEP. If its low, then there is something wrong. If it is High, change the mic and turn up the dynamic all the way.
Next. Have you been messing around in there?? Tryin to get more wattage? You turned VR4? If you thought you were turning it up by turning it all the way to the right, you turned it all the way down. Turn it all the way to the left.
SOURCE: replacement meter swr/rf meter for 25,29 gtl cost
for about 6 bucks on ebay you can get a new meter that lights up in blue i bought one looks cool
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