SOURCE: cobra 148GTL
Hello k007,
It sounds like you may have damaged the RF power amplifier stage of the CB. Since you were adjusting the antenna characteristics. Did you have a SWR (Standing Wave Ratio) meter connected while you were tuning the unit? If you did you might have noticed the needle go past the 1.2 mark when you were adjusting the antenna or the unit itself. In any event I think that the RF power Amp is shot.
Thank you,
Shuttle83
SOURCE: Cobra 148GTL Missing TX Modulation
The problem is most likely the audio ic . open the radio and see if the diode 44 is blown or see if you see anything that looks like it got hot around the plug area. if not contact me and i will buy it. is it an old or new 148 gtl.Read more
SOURCE: Cobra 148GTL can't TX on USB
Its the cap that feeds the first transistor to the first of the finals. It is either shorted or burned out.
Or the audio IC. It could be putting just enough out on AM to seem like its working, and then not enough for side band.
look at the caps near the finals. Look for a burn one, or one that could be twisted, or shorted in any way.
SOURCE: I have a cobra 148gtl that has 26 meg and high
VR10,,tuneL37,L38 you can remove TR24 it's for
modulation,but it may over modulat if removed.
that will get you started.
SOURCE: where can i find a service manual for a cobra
Contact the cb shop @ 317 426 9649 They have copies of manuals for pdf type formats..
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