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Uniden Washington

Discussion in 'General CB Services Discussion' started by Ben Hebert, May 26, 2018.

  1. Ben Hebert

    Ben Hebert Active Member

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    I have a Washington that transmit on am and lsb great but nothing on usb? Any help is greatly appreciated


     

  2. kaos513

    kaos513 Well-Known Member

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    Does the radio have power when you transmit?
     
  3. Ben Hebert

    Ben Hebert Active Member

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    Nothing on usb.
     
  4. sp5it

    sp5it Master of puppets

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    What is a voltage on L22 when USB rx?
    Mike
     
  5. Ben Hebert

    Ben Hebert Active Member

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    I don’t know
     
  6. sp5it

    sp5it Master of puppets

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    Measure it.
     
    PoDuck and ShadeTreeMechanic like this.
  7. Ben Hebert

    Ben Hebert Active Member

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    I will be able to when I can find time after work
     
  8. Ben Hebert

    Ben Hebert Active Member

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    What should it be?
     
  9. kaos513

    kaos513 Well-Known Member

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    Does your radio have a udp or mb pll?
     
  10. Ben Hebert

    Ben Hebert Active Member

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    What does Itlook like
     
  11. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    Header says Uniden Washington, so it'll be the MB8719 PLL.

    At L22, it should read 8 volts.

    ~Cheers~
     
  12. Ben Hebert

    Ben Hebert Active Member

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    If l22 has the right voltage what would be next to check? And if l22 doesn’t have the right voltage what to do next?
     
  13. nomadradio

    nomadradio Analog Retentive

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    What 'turns on' the correct circuit features to get USB is the mode selector switch. Has two sections. Section #1 sets up the power stage of the radio's transmit side. Section two feeds voltage either to the USB or LSB side of the two crystal-oscillator circuits.

    The NOT-banded end anode) of D22 is connected to one end of L22. Should see around 7 Volts DC, plus or minus where they connect to each other. But only in USB mode. Should drop near zero for LSB and AM.

    If it's not there, next question is why. If you have voltage in either of the other two modes, that's not right, either.

    My suspicions instead lie with the 7.8 MHz crystal oscillator. The banded (cathode) end of D33 should also have around 7 Volts DC in USB mode, both receive and transmit. Should drop to about zero in LSB trans/rec and AM receive. You should see that 7 Volts DC there ONLY while in transmit for AM.

    And if that one is wrong, the next question is why?

    73
     
  14. Ben Hebert

    Ben Hebert Active Member

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    L22 has 7.70 volts when on usb. Can’t find d22 to test
     
    #14 Ben Hebert, May 29, 2018
    Last edited: May 29, 2018
  15. nomadradio

    nomadradio Analog Retentive

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    D33 is the one I'm wondering about. D22 is at the same spot in the circuit where you showed voltage in USB.

    D33 is just about dead center of this pic.

    [​IMG]

    73
     

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