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Is there a way to read the L and C values of the ATU and/or to manually set them?

I have a 6400 feeding a 132 ft. end-fed antenna. Using the ATU it takes several attempts on 75 meters to get a good match. I'd like to lift the hood and see what the atu is doing.

Best Answers

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    edited April 2021 Answer ✓

    @rssutton9 What version of SmartSDR are you using?

    Also, don't for the internal tuner is only designed to do an 3:1 SWR or less reliably. Don't confuse the ATU in the 6400 with a proper antenna tuner that can far exceed that operational range.


  • John KB4DU
    John KB4DU Member ✭✭✭✭
    Answer ✓

    This is a common limitation of internal tuners. They are intended to support operations with an antenna that is resonant in the band but is being used at a frequency slightly off the resonant point. An end fed antenna could have a feedpoint impedance of 3000 ohms or more (60:1). Its going to need an impedance matching transformer.

  • Mike Steventon
    Mike Steventon Member ✭✭✭
    Answer ✓

    On page 13 of the 6400 and 6600 user manual it quotes:

    8.3 - 300 Ohms (80m – 10m) 6.7 - 150 Ohms (160m and 6m)

    -for the atu range.

    I find it quite good on my long wire, but you cannot beat a decent manually operated Palstar AT2K to have control over the rubbish I erect in my back garden!


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