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Thread: kenwood troubles

  1. #1

    kenwood troubles

    I recently was able to pick up a nice Kenwood ts-940 and it was working great until.......
    At a recent contest a few of the guys decided to hook up a amp to the rig now as soon as I turn the rig on it goes into transmit and doesnt come out of it
    Anyone else ever have this problem and if so were you able to fix it?

  2. #2
    Pope Carlo l NQ6U's Avatar
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    For clarification, does it do this even when it's no longer hooked up to the amp?
    All the world’s a stage, but obviously the play is unrehearsed and everybody is ad-libbing his lines. Maybe that’s why it’s hard to tell if we’re living in a tragedy or a farce.

  3. #3
    Yes no amp hooked up and as soon as it powers it goes into transimit

  4. #4
    La Rata Del Desierto K7SGJ's Avatar
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    Not having a schematic handy, my first guess would be to look for a problem in the T/R switching circuitry. If it's switched by a relay see if the relay driver is shorted or just biased on all the time. That should get you traveling in the right direction. Use the block diagram to get a general idea of how the switching is done, and then use the schematic to take you to component level.
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  5. #5
    Thankyou will start looking in that direction

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    Administrator N8YX's Avatar
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    Which model of amplifier was hooked to the '940, and how was this done - directly, via an isolation device such as an ARB-704?

    And the most obvious question: Has the "Send" pushbutton on the leftmost side of the rig somehow become engaged?
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

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    Not familiar with that radio but maybe there's a jumper on a connector that needs to either be removed or added?

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    A quick Google search suggests maybe a defective Q29.

  9. #9
    Pope Carlo l NQ6U's Avatar
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    If the amp was an older one, it's possible that the T/R switching ran at too high a voltage for a solid state rig. For instance, on an SB-220 amp, the no-load voltage at the T/R relay jack is well over 100VDC. That could easily fry a transistor on your rig, which was probably designed for around 25V max on the T/R circuit.
    All the world’s a stage, but obviously the play is unrehearsed and everybody is ad-libbing his lines. Maybe that’s why it’s hard to tell if we’re living in a tragedy or a farce.

  10. #10
    Yes I believe it was a old amp and I have started to look at the TR circuitry it definitely shorted something to ground to bring it into tx mode

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