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  1. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    No doubt working on a CB isn't as simple as a AM standard broadcast radio where the listening frequency is basically determined by a variable capacitor, a CB is a little like a FM radio in some ways but totally different in most ways as it works by modulating the amplitude not the frequency. I...
  2. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    One other thing I meant to ask, I adjusted the voltage of the VCO like it showed in the one message you sent, it started out at just over 2 volts but it came down to 1.5 adjusting L6, question is that was on channel 1. it changes with every channel, from what I read online that's normal...correct?
  3. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    I received mics with the radios when I bought them and from what I can tell they seem to work ok...I got the 2nd one on the bench this afternoon and found exactly the same thing with it, bad solder joints but a lot more than the 1st radio had however this one seems to work a better as it...
  4. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    I removed the plate on the solder side of the board under the exciter and powered it back up, with it removed and it worked, flipped it over to the component side and it quit again so I re-soldered all of that area and now it works BUT it appears someone has been inside there messing with things...
  5. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    Thanks for all the information Andy!!..this is the radio I have, looks exactly like the one you posted pictures of. I can change channels up and down and the display works fine, I checked the 10,24 with my scope and don't see a signal there but it must be there because the display works, I'll...
  6. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    I also cleaned all the glue off both sides of the circuit board when I had the IC out.
  7. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    I have another 19+ that works OK but the radio looks like it was run over by a truck, I took the PLL IC, 10.24 mhz crystal, and variable cap out of that radio and put it in the non working one but it still acts the same also I injected a 10.24 mhz signal into the DO pin of the PLL and I did get...
  8. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    Thanks for the schematic Mike, that will help a lot.
  9. L

    I'm in need of a schematic for a Cobra 19+ with a C5121 PLL

    Does anyone have any idea where to get a schematic or service manual for a Cobra 19 plus, from what I've read its the late model as it has the C5121 PLL IC...I have 2 radios like this I found at a rummage sale for a little of nothing but neither will transmit or receive as the 10.24 Mhz osc is...
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