Question about Cobra 148 GTL 120-Channels Base CB Radio

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Huge static busts

A while ago my Cobra 148 was borrowed and wrecked. From what hes told me he reversed the polarity "by accident" im just wondering if there is a dummy diode or other saftey features to stop perminent damage. Cheers. Dan

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Like Benimur said, most all newer units have a protection diode that is there for the purpose of protecting the radio when the power cord is pluged in backwards. It doesn't take much to fix them, only a $.02 diode. Most cb shops only charge between $10 to $15 to repair them.

Dean
Rollin CBs
Mt. Vernon, TX

Posted on Jan 23, 2008

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Hi,

Most if not all CB radios have a reverse protection diode soldered immediately right after the power connector. Its purpose is to provide a practical short if the wires are connected wrongly to a power source. This would cause the fuse to blow. The diode normally goes bad after a reversed polarity connection and therefore would need to be replaced. This diode is not in series with the B+ line but connected parallel to the power.

In some instances, other components would also fail: Power capacitors, Audio IC, TX finals and/or the switching/regulator IC.

Hope that this be of some help/idea. Pls post back how things worked out or should you need additional information.

Good luck and kind regards.

Posted on Dec 17, 2007

  • Louie  Role
    Louie Role Dec 23, 2007

    Hi again,

    How's the Cobra, any development(s)?

    Cheers.

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No non at all. Think im gonna have to send it off to be honest. If the protection diode had blown i dont think i'd get any life from it at all. Thanks for all your help though. Great site!
Dan

Posted on Dec 23, 2007

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1 Answer

Have a cobra 148 boughtat local market d expect much told it was a fm rig so i have recieve i have a reverse tx key it is uniace mic 4 pin a question of reversing tx pins in mic many thanx martyn


Go to www.cbtricks.com go to radios and schematics then go to C look for Cobra look for 148 then from there get the mike wiring diagram and you should be in business.

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does it light up the front panel? If not did you accidently touch something that created an overload that may have caused the reverse polarity diode to blow?

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Check first your microphone

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• check for continuity ( mic and cable )



If you have not done these steps,

try it first, or borrow other compatible mic for Cobra 148GTL

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Jul 28, 2012 | Cobra 148 GTL 120-Channels Base CB Radio

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My cobra 148 work well on am but not on lsb


clipping the limiter should not have prevented tx on sideband are u sure u didn't do something more accidently. r 131 is the correct limiter for the 148. just out of curiosity what year 148 is it?

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