I forgot to mention, if it's not practical to replace a long unshielded Ethernet cable, you can easily install these effective Ethernet RFI filters:
https://www.dxengineering.com/parts/dxe-iso-plus-2 Long ago I attempted to use turns of Ethernet cable wrapped around Mix #31 split ferrite beads on both ends of a long 100 Mbps unshielded Ethernet run, but it didn't help much. These DXE filters worked much better. 73, Bob, N6TV On Thu, Jun 11, 2020 at 12:50 AM Bob Wilson, N6TV <[email protected]> wrote: > *Summary*: > > To avoid 20m narrow band RFI generated by the KPA1500 and other Ethernet > devices, use shielded Ethernet cables, CAT5 STP or CAT6 STP, instead of > CAT5e UTP or CAT6 UTP. > > *Details*: > > The KPA1500 and some SDRs provide a 100 Mbps Ethernet port, which may be > tempting to use instead of USB in some situations. However, if you > connect an "ordinary" CAT5e UTP Ethernet cable (unshielded twisted pair) > to the amplifier, and your antenna is anywhere near the shack, you will > probably hear steady carriers around 14.029.5 MHz (plus carriers from any > other Ethernet devices in your house, or your neighbor's house, that are > connecting at 100 Mbps). I have not observed any HF carriers from > devices connecting at 1 Gbps, but the KPA1500 does not support 1 Gbps. > > This is illustrated by the following P3SVGA screen capture (the unshielded > Ethernet cable was short, only 1m long): > > https://www.kkn.net/~n6tv/KPA1500_RFI_from_3_ft_UTP_Ethernet_Cable_N6TV. > png > > My 20m antenna was cranked down, located 9m directly above the amplifier. > > The (weak) Ethernet carriers are visible even when the amp. is OFF. They > disappear completely when either end of the Ethernet cable is disconnected. > > I replaced the 1m CAT5e UTP cable with a slightly longer 1.5m CAT5 STP > cable (*shielded* twisted pair), and the KPA1500 carriers were not > detectable.. > > *How to tell if an Ethernet cable is UTP or STP*: > > Often it is printed on the cable, but it's easier to simply look at the RJ-45 > connectors. If you see clear plastic on three sides instead of shiny > silver metal on three sides, it is unshielded (UTP) not shielded (STP). > Most Ethernet cables are UTP, because STP costs more. > > *How to tell if a device is connecting at 100 Mbps or 1 Gbps*: > > Implementations vary, but most modern Ethernet switches and Routers have > one or two LEDs on each jack that indicate the current link speed. My > Netgear GS105 switch is clearly labeled (both LEDs green = 1000 Mbps, one > LED green = 100 Mbps). > > 73, > Bob, N6TV > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
