40m VDSL filter for your NBN (FTTN)

 Geoff VK2WA  pointed me to a blog posting from Andrew VK3FS

for filtering the VDSL signal hitting 40metre band for NBN FTTN connections.

A 40m VDSL filter to stop Internet drops. Works with TP-link Archer modem
 

I having the same plus more, not so much noise  eminatiing from the VDSL mode, but my RF crashing my VDSL, 

but first, the trick I did to crush the RFI radiating  from my VDSL connection and  my VDSL modem, I just add some clip-on  ferrites cores on the VDSL cable as it popper out of the wall heading to the VDSL modem, I just added the camp over ferrites one at a time, each time checking the internet download and upload speeds, I was getting 55Mbps download, for a 50Mbps NBN service, I hit a point where the dowblaod and upload speeds dropped, then removed that last ferrite, returning to a 555Mbps download and 19Mbps upload> now I could not detect any RFI from my VDSL FTTN service. 

Next problem,  crashing the modem, if ran on any HF band,  I only needed 5watts  to reset the modem, from any HF band,  so I started adding ferrites on the cables coming from the modem internally,  winding multiple turns on large size clampon  ferrites yielded good results, now I can safely run 50w on Tx on any HF band.  To improve on that, if I isolate the internal copper pair wiring within the house I can then run the 100watts.

End of 2024, full FTTP arrive in our street, just a matter of switching over to FTTP service to see what happens then.

update on RFI from Northern Beaches Hospital

 update on RFI from Northern Beaches Hospital

I wrote last year about tracking and identifying some RFI being emitted from Northern Beaches Hospital in Frenchs Forest, the good news is that it is fixed, I estimate  it was fixed in end of January or early February 2024,  I can now scan 6metre FM repeaters again wiithout being plagued by the bursts of noise.

RFI radiating from our local hospital

 

FYI to any others in the Frenchs Forest area (or near a large hospital) as I am seeing interference across 6metres and beyond being emitted from the Northern Beaches Hospital  

This is something I noticed over 12months ago, it was not always there  but became more prevalent 6 months ago, I presumed it was someone's rogue solar panel inverter as it only seemed to appear during the day, but then I started noticing it at night, which led me to do more sniffing, so I used the spectrum display on my ic756 to see that it was blobs of noise about 25khz wide, spaced approximately 100khz apart, spreading from about 45 MHz to 60MHz, and it has some drift in it. It could be radiating across a wider range than 45-60MHz, that just happened to be the limit of my radio's receiver.  I could NOT detect the RFI below 30MHz, and could NOT detect the RFI at 144MHz and above.

I decided to go mobile in the local area, to find that the strongest signal strength is coming from the new hospital, then doing sweeps driving around the hospital, the strongest signal was found to be from the western side (60/9) and weakest point is on the eastern side (s1). It not like a data signal, it just blobs of noise.

I think it probably some sort of medical equipment up on the upper floors on the western  side radiating RFI. It seems to start up around 9am in the morning and may stop  as late as 10-11pm

I was discussing this with Mike VK2EK, he said he seen similiar type of signal out at Windsor, then noted he can see the hospital out there. He is going to go mobile to further investigate his RFI source. 

At this point in time it is probably a common piece of equipment used in hospitals, and I know it won't be a Diathermy machine, this RFI is from something else that radiates nicely on VHF Low band.

Next step is try to take something portable to the hospital to do some sniffing internally without getting arrested. Then once I am satisfied of where it is located in the building I can report it to ACMA.

RFI/EMI from Inverter type Air Conditioners

 We replaced our 20 yr old Daiken R/C A/C for a new 18kW Daiken 'Inverter' type R/C A/C a year ago, I discovered this new A/C is very noisy on HF bands, particularly across 7 MHz and 18 MHz, the new Inverter type A/C are more efficient at heating and cooling,  however, the tradeoff is that the external compressor  unit is radiating RFI (Radio Frequency Interference) and EMI from either the Inverter Power supply or the DC fans.   It's bad enough dealing with RFI from damned solar panel Inverters, but at least dealing with  a RFI source in my own place is easier than solar panel Inverters on someone else's roof.

The main times we use this A/C is in middle of winter and summer. At first I did not suspect the RFI was coming from the A/C, as if I switched it on or off, I would not see any change to the RFI at the HF receiver, as I discovered after many attempts, that there was a delay of a few minutes, i.e you switch on, the compressor unit  it does not come on instantly and when you switch off, the compressor does not stop instantly. It took a while to catch on that it was indeed the A/C unit. Then I did various tests to determine from which end of the system, the internal blower unit or the external compressor unit was creating the RFI, it  was pretty easy to determine it was coming from the external compressor unit. I remembered the A/C installer saying these are all Inverter type systems. That triggered my memory about friends working in commercial radio comms saying they use these Inverter A/C systems out on remote comms sites to cool  the equipment in the comms sheds and that they create RFI. Now, I at least knew that the external compressor unit looks like the place where the Inverter Supply is located, or whatever is generating RFI hash is in the external unit.

I did a search on Google to see if anyone else discussing this type of issue and to see if anyone had some good ideas to fix it. For myself, I presuming I need to make use of some ferrite cores in the right place to knock down the interference. Found someone discussing his issue with his Fujitsu Inverter A/C system, so definitely a common issue. Plus some videos and a white paper on the topic. The Mitigation video gives the detailed technical understanding the issue and solutions.

Fujitsu inverter air conditioner radio interference - Fixya

Application_guide_aspects_of_electromagnetic_compatibility.pdf (abb.com)

Ruud Air Conditioner (HVAC) Radio Interference - YouTube

Mitigating Residential Heating, Ventilation and Air Conditioning (HVAC) RFI - YouTube

Improving receiver performance for Pi-Star MMDVM hotspots

 Since on the subject of my Pi-Star MMDVM hotspots, here is a tip for improving  the receiver performance if you running multiple hotspots of even a single hotspot in a high RF  environment.

Remember these MMDVM hotspots and even the other hotspots like OpenSpot have a simple wide-band receiver which can be easily overloaded, one thing I noticed when running my MMDVM in P25 mode was that  I was getting a lot of artifacts on my transmissions from my Motorola handheld when I operated in the same room or nearby rooms to my hotspot, it was much better when I operated from outside my house or other end of the house. First I thought don't use the little attached external antenna, but even when using just the onboard cct board antenna I could still overload the receiver up close  and I also noticed that when my DMR hotspot was transmitting I was getting errors on P25 receiver, even though the two hotspots operate almost 20MHz apart, I had all my hotpots running off the same USB power adaptor and I could get different behaviour by moving them around.

I decided to try some ferrite core clipons on the USB cables,  this was because I realised I could hear the USB power adapter noise getting into my HF receiver and it varied as I moved the hotspot position around, so I added some big clip-on ferrite cores and wrapped the USB cable through the hole a few times and experimented for best and minimum  effect on HF, I cleaned up all the noise. I was not quite sure who was the main culprit, so I added the multi-turned ferrite end of the cable closest to the hotspot. 

Later and purely by accident,  I was playing on P25 and noticed I not getting the errors I was previously getting, as normally I could not run my Motorola handheld in close proximity without getting artifacts on my transmissions, I also noticed the DMR hotspot now not de-sensing the P25 hotspot. This proved the hotspot receiver was picking up RF via the USB power connector, from this I made sure all my hotspots had a either toroid or big chunky ferrite clipon (14mm ID) with several turns of USB cable and fitted as close to the hotspot power connector as possible,  Now I can operate ether either DMR handheld or P25 handheld in reasonably close proximity to the hotspot without interfering (desensing)  with the reception of opposing hotspots. I also added smaller 3.5mm clipon ferrites at the power adaptor end of the USB cables.

It was a win-win situation, I reduced noise affecting my HF receiver radiating from hotspots and USB power adaptor and improvement of receiver performance of my hotspots by reducing receiver desense from other hotspots RF entering via USB power cables and localised RF from handheld transceivers. In terms of the MMDVM boards, if operating in a high RF environment, you are better not to use the external antenna, just use the on-board cct antenna. Only use the external antenna if operating out on low noise floor environment like a farm. Also if you running multiple hotspots, try to separate them from each other, the further the better, remember even with mW transmissions, the signals are still flattening each other's receiver front end at close proximity.

RFI/EMI from solar panel inverters

 Well, it had to happen, the increase of people  installing f%$#ing solar panels on their roof, because they "think" they are saving the world, has wiped out my HF reception. There are a couple  houses across road from me, but I haven't had an issue with them, even the Tesla driver with his whole roof covered. But a couple weeks ago I noticed noise level on 40m jumped to s6 and pretty consistent each day, it can seen on the spectrum display on my HF, it is inverter noise,  

I spent a day turning off and unplugging everything in the my house to see if I was the source, nope. Got up on roof, spotted a house  diagonally over back fence with a brand new set of f#$%ing solar panels, they weren't there, when I last up on the roof a few months back. Here's hoping the inverter isolation safety switch malfunctions and burns their house down.

Now I understand why the big push from ACMA to introduce a Class license system for Amateur Radio operators, the ACMA knows what is going to happen, lots of RFI/EMI complaints from faulty or cheap solar panel installations, once we are a Class license, then we can't complain about interference, it becomes  "your problem, you deal with it!"

Another problem the Greens have inflicted on society. Having done work for govt corruption bodies, I know what the Greens do and how they operate. It's a shame nobody will take steps to shut them down and put them in prison for their criminal activity. I can assure you The Greens are not the smiley faced do-gooders they make themselves out to be.

new source of RFI (Radio Frequency Interference) LED signs

 Here is a short video showing some RFI coming from a LED sign from local club member, when start to look around you find many of these signs at schools, churches and shops.

This example is listening on a 2metre band FM radio.   It be nice to find the manufacturer to let them know these signs are radiating RFI.

IMG_2254.MOV - Google Drive

RFI from Foxtel IQ2 STB's on 10m & 6m bands

I noticed hearing modulated signals across 29 MHz band and 52-53 MHz bands when scanning the FM segments from time to time, not clean carriers but data  modulated carriers appearing then disappearing.  By accident, I just happening to hear this occurring one day and by chance doors were open in the house where I could see through doorways to the TV set where the XYL was flicking through Foxtel channels.  OMG, the modulation on the signal varying as channels are being changed, here was the culprit, our Foxtel IQ2 STB (set-top-box).

I got out the Uniden handheld scanner and did some sniffing around the  STB, but no, it seems to be radiating from the LED flat panel TV,  turned power off to the TV but noise still radiating, unplug power cable from TV and noise still there, unplug HDMI cable to Foxtel STB, then RFI signal drops off drastically.

Sniff closer to Foxtel box, very strong signal from the ethernet RJ45 cable and the HDMI cable.  Remove both cables and noise almost non-existant.  sniff the power cord at the rear of Foxtel STB and noise still very low,  plugin the HDMI and ethernet cables one at a time, pretty equally as strong.
I noticed it detected noise on 2m band too, but much lower levels than that of 10m and 6m bands.

Outcome, the Foxtel box itself not radiating but very bad when HDMI cable plugged into a LED flat panel TV, as it using the TV as a RFI antenna.  As a secondary source of RFI it using the Ethernet RJ45 cable as a nice antenna too. I think from memory the IQ2 box made by Pace.

Solution, grabbed my box of various  sized ferrite clipon cores, added 7mm ID and 9mm ID cores on the power, RJ-45 and HDMI cables, closest to the rear of the Foxtel IQ2 box, this suppressed the RFI  sufficiently, in terms of 10m and 6m bands, could now only receive RFI up to about 1 metre from the STB, whereas my  transceiver antenna could hear it from 20 metres away.   I also tried clamping some ferrite cores over the two coax leads running to the satellite dish LNA but that made absolutely no difference, so RFI not radiating back out via coaxes, that I could see.