Flex 6600 network packets are dropped when transmitting on 40 meters

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I have set up my Flex 6600 to use WSJT-X->HRD->SmartSDR Cat (CAT, Serial, FlexVSP, COM5).  It seems to work fine except on 40 meters.  On 40 meters, when transmitting, network packets are dropped and sometimes they are dropped to the point of losing communication and I've seen SmartSDR terminate. I'm guessing there is interference on the Ethernet cable that is only problematic at around 40m.  I did switch to using the CAT 6 cable included with the 6600, but the problem persists.
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Bogfog

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Posted 4 months ago

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Steve - N5AC, Employee

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I don't know of anyone else having a similar problem.  We do have diodes to limit the energy on the Ethernet interface, but this doesn't mean that the RF will not distort the data and possibly cause a loss of connection.  I would recommend 1) you use all CAT5 or better cables, 2) check the power supply on any routers/switches to verify that they are not picking up RF and if they are, place chokes/ferrite on their power supply lines, 3) remove any unterminated Ethernet cables from switches and routers, etc.  If all else fails, you can try some mix/match with your network to locate the problem (remove the switch and go direct from 6600 -> computer.  If this fixes it, it may be in your switch, etc)
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Tim - W4TME, Customer Experience Manager

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...and some switch/routers are more susceptible to RFI ingress than others.  Using a switch with a metal case does help in high RFI environments.

In general, this is probably common mode currents coming down the coax and looking for a path to a lower ground potential.  Using a common mode choke on your coax and grounding the coax shield to a good RF ground before it enters your dwelling is very effective in shunting common mode currents to an earth ground which is the lowest of ground potentials.

This is a really good article that explains RF grounding
https://helpdesk.flexradio.com/hc/en-us/articles/204779159-Grounding-Systems-in-the-Ham-Shack-Paradi...
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Bogfog

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After re-examining and fiddling with the grounding I could see the problematic frequencies change from 40 meters to 15 meters.  Adding the common mode choke on the coax solved the problem and now it seems to be working well on all bands.  Thanks!

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