Amateur radio interference to NBN (VDSL2) connection in Australia

From time to time I transmit on the 80m and 40m band. The frequencies in these bands overlap with the frequencies utilised by the NBN here in Australia. The NBN in Australia utilises VDSL2 often using the existing copper phone line for the final stretch from the node to the premises – in my case the final 700m.

When I first started transmitting I noticed my internet connection would drop. After a bit of experimentation I found that I can see the interference in the admin screen of my modem (FRITZ!Box 7490).

Here is what the SNR graphs look like steady state

When I transmit on 80m or 40m there is plenty of interference introduced by the transmitter as seen in the following screenshots.

Test transmission on 80m
Test transmission on 40m

I have just finish studying for my Advanced licence and so have had the ear of a few people with the extensive knowledge on all things interference lately. They kindly suggested winding the phone line around ferrite rods which I tried (clump of 4 rods with 5m of phone line wound around it) but the internet still drops when I test transmit 100W CW, have also added various values of capacitor in shunt between red and green phone line. As can be seen from the following screen shots, the various capacitance have some fairly dramatic impacts on the bandwidth that is available to the connection and hence what speeds I get on my VDSL2 (NBN) connection.

20,000pF resulted in 11.05MBits Down and 1.45kBits Up

20,000pF in shunt – really knocks the internet connection around. notice only have 1 download and 1 upload band

10,000pF results in 14.MBits Down and 3MBits Up

1,000pF results in 26MBits Down and9.7MBIts up

33pF its getting back to normal now 41MBits Down and 11.5MBits Up.

I hope there are others out there that find this page and it can assist in identifying issues you may have and what doesn’t seem to work for me. If you have any suggestions on what will fix this persistent issue I’m all ears.

2 Replies to “Amateur radio interference to NBN (VDSL2) connection in Australia”

  1. I’m wondering if you ever got your NBN RFI issue sorted out?
    I have the same problem and have tried everything to no avail.
    Next mission is to try and get band notching applied to the modem, but trying to find someone at Telstra to talk to and who understands what I require is going to be a bigger issue.

    1. Hi Craig. Jeepers, so sorry for delay in reply.
      I never did sort out RFI problems on the modem when TX on 160 or 80m and to be honest started operating with a yagi good for 20, 15 and 10m only so the issue was overcome that way. That said, the council has since forced me to pull the Yagi down so I’m not operating from home at all now days.
      I did receive some corro from Craig – VK3CRG who apparently had some success getting band notches applied to his FTTN line by NBN which must have helped. Perhaps reach out to Craig to learn more mate.

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