Question about Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

Keys up and everything dims and does not transmit.

On occasion, my 148 Gtl will suddenly dim the meter light and the led light while I am keying up the mic. When this happens, I cannot transmit and the meter barely moves. To solve this, I turn the volume knob to almost turning off the radio and then everything brightens back up and I am able to kick out a strong signal. The mic seems to work fine, but I am planning on trying a different mic as soon as I can find a 5 pin mic. The Mis is an echo and talkback mic, and I think that it might be related to the mic, if not something internal lot the split shaft pot on the volume/squelch knob.

Any ideas?

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  • creole Mar 19, 2008

    My handler is creole from Trinidad. I am also experiencing similiar problem with my 148gtldx, when i turn on my radio the meter light is dim and i have to turn it on an off couple of times to get the full brightness. So now i just leave the rig on and disconnect the power cord if needed. There's is also a problem when transmiting on the AM, i've been told there's a scratching squeal sound coming with my transmission. The technician said he change the final ic' and fixed some cold solder, but no improvement. Can someone give help/advice?

  • SHARCNET-USA
    SHARCNET-USA May 11, 2010

    Moving the volume/on/off knob to make the radio work again is interesting and a good clue. On most CB's, the pot is probably soldered directly to the printed ciruit board.



    It's possible that there is a bad solder joint to the power connections on the pot that turn the radio on & off. If the solder joint is bad, it can still make a connection but the connection will have added resistance in line. The on/off switch can be bad too.

    Switches arc each time they are used and over time, the contacts become pitted and make poor connection.



    I had a stereo receiver where the tuner lights flickered and there was electrical noise in the receiver. It turned out to be a bad on/off switch.



    This resistance may be low enough not to affect the radio when in the receive mode but when you transmit and draw more current that resistance will be noticable during transmit.



    The fact that you rotate or move the volume/on/off knob and the radio starts working again, tells me that there may be a bad connection in the radio.



    A cheap thing you can try is spraying some electrical contact cleaner into the pot and rotate the pot back & forth several times and turn the switch on & off several times to clean it.



    Please let me know if I can be of further assistance to you.



    Good luck!



    - Jim

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Moving the volume/on/off knob to make the radio work again is interesting and a good clue. On most CB's, the pot is probably soldered directly to the printed ciruit board.

It's possible that there is a bad solder joint to the power connections on the pot that turn the radio on & off. If the solder joint is bad, it can still make a connection but the connection will have added resistance in line. The on/off switch can be bad too.
Switches arc each time they are used and over time, the contacts become pitted and make poor connection.

I had a stereo receiver where the tuner lights flickered and there was electrical noise in the receiver. It turned out to be a bad on/off switch.

This resistance may be low enough not to affect the radio when in the receive mode but when you transmit and draw more current that resistance will be noticable during transmit.

The fact that you rotate or move the volume/on/off knob and the radio starts working again, tells me that there may be a bad connection in the radio.

A cheap thing you can try is spraying some electrical contact cleaner into the pot and rotate the pot back & forth several times and turn the switch on & off several times to clean it.

Please let me know if I can be of further assistance to you.

Good luck!

- Jim

Posted on Feb 08, 2008

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