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Flex -6300 sometimes gets stuck on tune. Clicking the tuning button does not stop it.

The Flex has never done this before. I just added a 4/1 unun to my 33 ft. vertical. I had been using a 9/1 unun that worked well. I decided to go with a better unun for a vertical. Trying out 40 meters worked well until I turned on my amp. Then I went to tune and hitting the tune button would not turn it off. As soon as I turned off the amp the tune button worked. Did it in 20 meters as well. I haven't tried other bands yet. Any one with a suggestion as to why this is happening would be welcomed. I tune with less than 15% power. Transmitting too much power on tune? Something wrong with the amp? It's a Tokyo HY-POWER HL-550 FX that has worked flawlessly. LDG AT-600pro Tuner. Balun Designs 5K 4/1 unun.  Thanks.  


  • Dan Buckheit
    Dan Buckheit Member
    edited May 2017
    Smart SDR v 1.9.13. Alienware PC 16 MB RAM 
  • Al K0VM
    Al K0VM Retired Member ✭✭✭
    edited November 2017
      I sounds like the 4:1 may result in more RF in  the shack which could block the PC or PC  to radio ethernet control..  Suggest the usual RFI fixes... Grounding .. ferites.. bonding.. etc..
    AL, K0VM
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited May 2017
    Agreed.  Divide and conquer.  Try the same process into a dummy load.  If the problem does not exist, remove the 4/1 unun and test or keep moving the dummy load down the coax until you can reproduce the problem.
  • Dan Buckheit
    Dan Buckheit Member
    edited May 2017
    Good ideas all. Thanks. 
  • Jim  KJ7S
    Jim KJ7S Member ✭✭
    edited January 2020
    I have had to force the amp in to standby when that happens and the other theories are correct, RF getting places it shouldn't.  Make sure things are grounded properly and you have no resonant harmonic lengths  of ground or feedlines as well.
  • Dan Buckheit
    Dan Buckheit Member
    edited June 2020

    I think we are on to something here. 

    Put ferites on the DC feed wires from my power supply to the Flex. Also on the cables to and from the amp and tuner. Checked grounds to make sure they are tight (ground is 8 ft copper rounding rod right 7 feet below the surface - outside the adjoining window). Only does it about 50% of the time now. I'll keep experimenting.

    Thanks for all your suggestions.  de KH6DAN     
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited May 2017
    Don't forget the Ethernet cable
  • Ken - NM9P
    Ken - NM9P Member ✭✭
    edited June 2017
    Also, I suggest using Mix 31 ferrites, rather than the cheap ones available in bulk at hamfests, unless you know exactly what you are getting.  The cheap ones are often designed for VHF/UHF and were created to help equipment manufacturers eliminate interference to TV and FM broadcast (the major complaints back in the day).    

    For common mode filtering, Mix 31 ferrites are generally the most suitable for HF from 160 Meters through 6 Meters.  Mix 43 may also be used for the higher bands above about 25 MHz.

    Many of the common flea market cores are Mix 43, 52 or 61.  Most of the cheap ones I have seen are 61, which are most effective from 200-2000 MHz.

    See here: 

    Many hams will buy use the wrong cores for Common Mode filtering because they were a "bargain" and wonder why they aren't very effective.

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