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Thread: President AX-144 critical help

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    354NYmudduck's Avatar

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    President AX-144 critical help

    Before I get started... not to be mean but this is an article for the veteran tech guys 25+ years of doing electronics and transceiver repairs and someone who has hi-tech test equipment at their bench.

    The whole radio powers up
    receive
    transmit
    all new electrolytic caps
    upgraded filter caps
    new pll chip
    new balanced modulator chip
    uograded power leads from power plug to the main board.
    Aftermarket bourns trimpots replacing the final and driver biasing controls.
    Tried replacing one crystal trying to troubleshoot
    And yes the radio was doing what I’m about to describe before all the update work.

    Radio and all features are functional. When transmitting on both usb and lsb there is a 25 watt carrier. Am there’s a carrier but no modulation or swing. The radio receives on one frequency when you transmit it goes to 27.5373mhz on all modes then back to whatever channel you were on originally. No matter where you set the final and driver biasing controls you can not eliminate the 25 watt carrier and squeal on ssb. The receive was also all screwed up until I got another pll chip out of a parts unit from a buddy. So I put another exact same pll chip in and the receive and carrier oscillator section is completely functional but as far as transmit goes there’s a 25 watt squeal and carrier and the unit is transmitting and receiving on two different frequencies.
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    Quote Originally Posted by 354NYmudduck View Post
    Before I get started... not to be mean but this is an article for the veteran tech guys 25+ years of doing electronics and transceiver repairs and someone who has hi-tech test equipment at their bench.

    The whole radio powers up
    receive
    transmit
    all new electrolytic caps
    upgraded filter caps
    new pll chip
    new balanced modulator chip
    uograded power leads from power plug to the main board.
    Aftermarket bourns trimpots replacing the final and driver biasing controls.
    Tried replacing one crystal trying to troubleshoot
    And yes the radio was doing what I’m about to describe before all the update work.

    Radio and all features are functional. When transmitting on both usb and lsb there is a 25 watt carrier. Am there’s a carrier but no modulation or swing. The radio receives on one frequency when you transmit it goes to 27.5373mhz on all modes then back to whatever channel you were on originally. No matter where you set the final and driver biasing controls you can not eliminate the 25 watt carrier and squeal on ssb. The receive was also all screwed up until I got another pll chip out of a parts unit from a buddy. So I put another exact same pll chip in and the receive and carrier oscillator section is completely functional but as far as transmit goes there’s a 25 watt squeal and carrier and the unit is transmitting and receiving on two different frequencies.
    Well if the balance osillator is good I would look for a sodder bridge some where close to it


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