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Weird problem running SmartSDR on 2.5gb local area network (Flex 6400)

Randy KN4YBA
Randy KN4YBA Member ✭✭
edited August 2022 in Networking

Hello all,

I decided to upgrade my Unifi network system this spring to the Unifi Dream Machine Special Edition and Unifi Switch Enterprise 24 PoE. I have a 10 GB fiber connection between the Dream Machine SE and Enterprise Switch with 2GB Google fiber internet interfaced with the Dream Machine. The switch provides me with 12 2.5Gb PoE+ ports and 12 1Gb PoE+ ports.

My desktop has a 2.5 GB Lan card installed and everything works great with SmartSDR until I get to around 17M to 10M. When I transmit voice or CW above 50 watts the SmartSDR will lock up on my computer for a few seconds. I also have a 1gb Lan connection on my desktop and if I swap the Lan cable from the 2.5Gb down to the 1gb port I no longer have this issue.

I don't have a shielded Lan cable running from my network room on the other side of the house to my office, and also restricted in only using attic antennas. I get the possibility of the 2.5 connection being more susceptible to RF but wondered if someone else may have seen this with a 2.5gb Lan connection?

Currently my workaround is small network push button network switch on my desk that I can just switch which Lan port on the computer to be used based on if I am transferring files to my NAS or connecting and transmitting on my 6400.  

Has anyone else experienced this issue connected to a 2.5Gb Lan connection and transmitting at 17M to 10M?





  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin


    It sounds like you have an RFI issue. Remember, every wire in your shack is also an antenna. Usually, it isn't an issue.

    I would start with choking some of the power supply cords on the network devices. You may be causing them to reboot.

    This is a great document on RFI and how to solve it. I would look there first.


  • Randy KN4YBA
    Randy KN4YBA Member ✭✭

    Thanks Mike!

    Living in an HOA with antennas in the attic, I have learned everything metal is a potential source for reflective RF back into my house.

    In my environment with antennas in the attic, everything gets a choke or two. I did the same with the Dream machine and Enterprise switch when I initially installed them. It really only seems to impact me when I am connected to my 2.5Gb port, but now I know the RF off the antennas are causing network issues that I was unaware of prior to installing 2.5gb system in my house.

    Thanks for sharing the document, and I hope to see you here in Huntsville next weekend at the Hamfest.




  • Mike, to follow up on what I did to overcome rf on my 2.5 GB lan to the office.

    I could have fought this issue for days, weeks, or months in and out of the attic, where all my antennas are located, and took the easy way out.

    I ran a 10gb multimode full duplex LC fiber from my enterprise switch in the network area across the attic to my office where my desktop and 6400 are located. I am now connected at 2.5gb to my computer and the 6400 is working great.

    In addition, I am getting my 2 full GB of internet connection in my office and the flex could not be happier.

    I am using the Zyxel Multi-Gig 12 Port Unmanaged Switch with 2 - 2.5Gb and 2 - 10GB SPF+ ports. In addition the switch has 8 - 1 GB ports.



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