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no modulation

Discussion in 'General CB Services Discussion' started by bluecurt63, Mar 16, 2019.

  1. bluecurt63

    bluecurt63 Member

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    ive got a brand new general lee just took it out of the box. It has no modulation on low power,ive checked the pots for low power . It keys up fine got good carrier on low power but no modulation.It works fine on hi power,got good modulation on hi power.but no mod on low power.


     

  2. nomadradio

    nomadradio Analog Retentive

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    The modulation limiter trimpot will cause this. It has a separate modulation limiter trimpot for low-power only. Pretty sure it's VR12. Any time the carrier-power setting for "Low" is turned down, VR12 can kill the audio if it's set too low.

    73
     
    kaos513 and OldTech03 like this.
  3. bluecurt63

    bluecurt63 Member

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    done tried it still don't work
     
  4. kaos513

    kaos513 Well-Known Member

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    Check power supply is enough for the radio.do some testing with Multimeter to power supply to radio.
     
  5. jessejamesdallas

    jessejamesdallas Sr. Member

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    Got the Mic Gain turned up?
     
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  6. nomadradio

    nomadradio Analog Retentive

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    Better yet, find the trimpot that sets carrier level on "Low" and turn the carrier up slowly while modulating the radio.

    Odds are you'll find the carrier level at which it breaks free from the limiter and the audio comes back. Since the radio modulates okay with a higher carrier level, we know all the other stuff is working okay.

    Unless the Low-side limiter pot is turned all the way to the wrong end. I'd start with the limiter trimpot set so the DC voltage measured on the face of the trimpot is as low as it will go.

    73
     

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