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Mfj model j993b auto tuner

Discussion in 'General Technical Questions and Answers' started by TINTOTTY, Sep 20, 2021.

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    Help, I wanted to hook my amp up to the mfj j993b auto tuner, so here's how I hook it up,outside antenna to antenna 1 on tuner,antenna side of amp to transmitter on mfj tuner, and radio transmitter to amp Rtx side of amp stayed the same when just using the the tunner works fine until I turn the amp on and the tuner quits working, I have no idea why this happens can anybody help, am I hooking up the cables right, I think I am


  3. W7UUU

    W7UUU Principal Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    What band are you operating? What model tuner? What model amplifier? What model radio? Presuming you have a load - dummy load?

    All of those could be factors in helping to answer your question

  4. K8XG

    K8XG XML Subscriber QRZ Page

    That tuner is only a 300 watt "tops" tuner. I assume then that you are using a low power radio into a small solid state amp designed to take the power up to 100 or 150 watts?

    You tune the tuner with the amp off via the RF of the radio in CW or AM; if it has enough power to trigger it, 10-15 ish watts.
    Then when the tuner is matching the antenna, then you turn on the amp.
    If your low power radio cannot make the tuner tune, then you would need to find a way using your "assumed" solid state pill amp to get about 20 watts out for tuning, you will burn the tuner up tuning at 100watts eventually. We had a new ham here that was doing it and burned the tuner up.

    At this point what part of the tuner is no longer working? The SWR changes really bad ? Does it start chattering on you?

    To tell you the truth, if your radio setup is like I have at the top, A low power 5-15 watt QRP radio into a Solid State pill type amp getting a manual tuner you can tune yourself at 5watts is a better deal than an auto tuner.
  5. N3PM

    N3PM Ham Member QRZ Page

    Page 22 of the manual addresses over-power shutdown.

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