Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

My Flex 6400 Tx is showing "hiccups" in its output waveform! Help, please!

I've been running my Flex 6400 for more than 5 years with great results -- over 16,000 FT8 contacts with few problems and the best DX I've ever enjoyed! However --

Please see the attached image of spectrum output into a 50-ohm dummy load. The output appears to be "hiccupping" periodically.

I have seen something similar in the past when I would run the rig 24x7 for days at a time. Based on an old recommendation from Tim, I learned that killing and restarting "DAX" would put me back in business. However this new "hiccupping" isn't cured with this method, making my think my beloved Flex 6400 may be dying of old age(?)!

Has anyone else seen this problem? Are there any things I might try to fix this?

Many thanks in advance for any suggestions!

73, Dave, N7DK, [email protected]


  • KT5N  Jeff
    KT5N Jeff Member ✭✭

    Same here with my 6500. I thought it was possibly coming from a malfunctioning remote antenna coupler but it persists while using the ZS6BKW as well. I am running 3.4.23.

  • Eric-KE5DTO
    Eric-KE5DTO Administrator, FlexRadio Employee admin

    First, I would recommend updating to the latest version (currently v3.5.9). There is a possibility this alone will address what you're seeing.

    If that doesn't get you going, to get to the bottom of this I might temporarily change the network setup to directly connect the radio to your PC. This will eliminate any other network devices/config between the PC and the radio. If this eliminates the issue, then it may be time to look at any cables and devices (switches, routers, etc) in the original configuration.

    Let us know what you figure out.

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    Besides WSJT-X, what other software is running? Anything changed recently? What version of SmartSDR? If you haven’t upgraded to the latest version SSDr, try that.

    Usually the “pops” which show as wide horizontal lines in FT8 happen when TCP commands are being sent to the radio while it is transmitting.

    Dave wo2x

  • N7DK Dave
    N7DK Dave Member ✭✭

    Replying to Jeff, KT5N, and Eric KE5DTO --

    Thanks, Jeff -- it's a comfort to know I'm not alone! I was theorizing I have a marginal/intermittent connection in somewhere in my shack connections & remote tuner (swr monitors, scope, tuners, linear, coax switches, ... ) so I just tried a dummy load on the radio itself -- and the problem persists.

    Thanks Eric -- I do have an older version of the software on the radio, and I'll try updating it. Because the "hiccups" occur even with a 50-ohm dummy load connected directly to the Tx output, there is something in the radio itself that has gone awry. I've been running the radio nearly 24x7 since April of 2018, so I've been guessing my final may be "aging out", but from comments of others, it seems more likely it's a software issue of some sort.

    I'll post again if I learn more ...

    73, Dave, N7DK

  • N7DK Dave
    N7DK Dave Member ✭✭

    Replying to David, WO2X

    I'm running Version 3.3.32 which is way out of date. It had been working so well that I didn't want to tamper with it. But the first thing I'll try is a software upgrade to the latest version.

    Thanks & 73 -- Dave, N7DK

  • KT5N  Jeff
    KT5N Jeff Member ✭✭

    So today I installed 3.5.9 and the pops went away!

    Strange thing is why they started in the first place.


Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.