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Horizontal lines in waterfall in new 8400, not other radios

I just booted up a new 8400 and I am getting horizontal lines across the waterfall every time I key my paddles (and in CWX ) . This suggests RF but the exact same antenna, feedline, and computer have no such issues when using a Yaesu and in the past with same antenna with a 6600 had no such issues. It happens regardless of RF power settings all the way to zero and on all bands (SWR <1.5:1 ) . The HF antenna has a Balun Designs RF choke in line . Also happens on a commercial 6M vertical with different feedline that has a almost 1.1 SWR. The 8400's ground terminal IS connected to an 8ft ground rod about 4 feet from the radio's window location.

I do have "show TX in waterfall " disabled .

Any suggestions where I start troubleshooting?

Andy K3UK

Comments

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Andy, those lines show where RX stops and starts when you transmit. They are normal and expected.

    If you stop the waterfall and scroll down, you will be able to see where you were transmitting.

  • Andrew O'Brien
    Andrew O'Brien Member ✭✭✭

    Hmmm, it has been a year since I operated a Flex, I don't remeber that. Old age setting in . That makes me feel better though . Thanks Len.

  • Andrew O'Brien
    Andrew O'Brien Member ✭✭✭
    Screenshot 2025-12-09 192010.png

    This is the waterfall after I simply sent "K3UK" . Does this seem normal?

    Andy K3UK

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Yes, that is exactly what I would expect. The longer you set your CW Delay, the fewer lines you get because the rig does not go back to RX as often.

  • Andrew O'Brien
    Andrew O'Brien Member ✭✭✭

    Thanka again.

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