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Shielded Ethernet Switch Recommendation

Doug Wilson
Doug Wilson Member ✭✭


I was having big rfi problems with SmartSDR and the 6600M (mostly transmit cutout) that have been completely solved with a Palomar 6600 kit and DX Engineering filters on the ethernet cable to the radio and computer.

Now I've noticed a spike every 60 khz or so on 20m that is stronger on the hexbeam than the efhw but present even with the antenna disconnected. Some searching reveals this could be unshielded cat5 but could also be the unmanaged switch I'm using.

Any recommendations on a shielded 10 port switch, or other solutions? I understand this could be several other things and I can work further to hunt it down. I'm in a pretty quiet rural setting with no neighbors closer than 1/2 miles so it's something here. So I thought I would try the experience base here for easiest fix first. The 61khz spacing sounds like the switch, cat5 or both but I don't know.


Best Answer

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


    It is likely from wall cubes, or something like a cordless drill charger. You may have to kill the power to the house and run the radio on battery while turning on 1 thing at a time.

    I doubt it is from the station power supply.



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

    Hi Doug

    If they are every 60Khz or so, it is likely a switching power supply.

    I bet they look like this. This is at my remote. I have to go track them down.

  • Doug Wilson
    Doug Wilson Member ✭✭

    Mine are not that pronounced (maybe half the db) and do not have that double spike. I'm using two Samlex 1235P-M power supplies and they could definitely be the source.

    I switched off the non radio power supply and the spikes were unchanged. However shutting off the tuner showed an 8db noise floor drop on the hexbeam.

  • Doug Wilson
    Doug Wilson Member ✭✭

    Thank you Mike.

  • frc2302
    frc2302 Member ✭✭
    edited May 9
    Sorry to resurrect an old thread, but just wanted to mention that you should be careful with shielded ethernet cables. Ethernet is ground-isolated by design, which in our case is a good thing. Adding a shield, if it is connected at both ends, may give you a ground loop, which may create new problems at best, or be dangerous at worst.

    I found that fiber is pretty cheap for small runs. You can isolate your ham gear from the rest of your network for under $100, including a pair of media converters, the necessary transceivers, and a length of fiber. That's the route I went, and it is of course immune to RF, ground loops, and surges.
  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    BTW, I am going to write this up in detail. First, the DX Engineering ISO filters did nothing to help in my situation. YMMV.

    I was dealing with the picture you see above with the feed to my tower (Shield CAT 6) being the problem. I did spend all day Saturday working on it. I got rid of a lot of the noise by changing the Switch to ProSumer switch (TP-Link TL-SG1024DE), but the noise continues.

    I will be changing it to Fiber once I get back from Dayton.


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