ICOM 756 pro II problem?

Discussion in 'Radio Circuits, Repair & Performance' started by CO8HF, Jan 20, 2021.

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  1. CO8HF

    CO8HF Ham Member QRZ Page

    Friends,
    I have an IC 756 pro II, which presents the following problem, its analog and digital meters indicate that the SWR is high and does not indicate output power, instead an external swr meter connected between the trasceiver and the HF antenna indicates swr 1.5 and 110w of power, I also have a 706 IC that when using it that indicates that everything is ok using its built-in swr and power indicators, could someone tell me what could be happening?
     
  2. W1NB

    W1NB XML Subscriber QRZ Page

    I suspect one or more component has failed in the internal bridge that the radio uses to detect standing wave.
     
  3. N1RND

    N1RND Ham Member QRZ Page

    Or....could something be wrong with the swr power fold-back protection circuit?
     
  4. N1RND

    N1RND Ham Member QRZ Page

    Wait, my bad, he did say the rig puts out full power according to an outboard meter.
     
  5. VE1IC

    VE1IC Ham Member QRZ Page

    does the built in tuner work? Look at the diodes or any damage on the CTRL board.
     
  6. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, look at the components in the internal SWR Bridge inside the rig . . . one or more has failed.

    Roger G3YRO
     
  7. CO8HF

    CO8HF Ham Member QRZ Page

    Thanks for the advice, all I appreciate, just one more matter, the ATU adjusts the antenna, but with a simple dipole antenna it does not present the problem, only with the multibands, even with a dipole fan it works well, it would be possible that you have a problem in memory and should I reset the program? to get started
     
  8. W1NB

    W1NB XML Subscriber QRZ Page

    I don't believe there is a memory problem. With a memory problem it would not recall settings that were stored after a successful auto tune session. If the tuner is searching correctly and achieves low SWR then it is working correctly. Keep in mind that the internal tuner on that radio is capable of tuning a worst case of 3:1 SWR. If you have an antenna with a higher than 3:1, odds are it will not tune it.
     
  9. CO8HF

    CO8HF Ham Member QRZ Page

    Thanks for the help, I upload images to explain
    Direct antenna without internal ATU on
     

    Attached Files:

  10. CO8HF

    CO8HF Ham Member QRZ Page

    Direct antenna with internal ATU on, it is seen that it does not indicate output power
     

    Attached Files:

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