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Realistic TRC-453, no modulation on AM, but SSB is ok.

Discussion in 'CB and Export Equipment and Accessories' started by Satelitte, May 30, 2013.

  1. Satelitte

    Satelitte
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    Hello everyone.
    I've got a problem with my Realistic TRC 453 (simillar to Uniden PC-122 Radio).

    It has no modulation on AM mode (carrier only), but on SSB mode everything is allright and modulated.

    So I am asking you. How I can fix it up?



    Driver, and PA transistors are OK.
    I picked a new capacitor 47uF near to the NE612 modulator and trying to resolder the area around.
    Turning the VR of AM mod changes nothing.
    :headbang

    Any ideas?

    73!
     

  2. sp5it

    sp5it
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    Master of puppets

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    Replace TR544
    Mike
     
  3. Satelitte

    Satelitte
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    That's it!
    After a quick measurement I see it can be broken.
    (Drivers of it seems to be ok)

    Will be replaced soon.

    Dzięki Michał. 73
     
  4. Robb

    Robb
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    Yup

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  5. Satelitte

    Satelitte
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    I'd rather put BD912 there. No problems with availability.
     
  6. Satelitte

    Satelitte
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    Hi guys it's me again.

    After replacement - it still doesn't work.
    There's about 8V when transmitting, on every single electrode of this transistor.
    It heats very much too.

    And there's only carrier and no mod.
     
  7. sp5it

    sp5it
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    Check TR36, 37, 38, D42.

    But first of it all remove C166 and check if there is any audio on R135.
    Mike
     
  8. Satelitte

    Satelitte
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    Still nothing... Can it be some issue with AM transformer? The carrier on AM is sometimes discontinuous.

    Thanks
     

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