Interference across 6metre band in Frenchs Forest area,

 Interference across 6metre band in Frenchs Forest, NSW area

Over last couple months the interference has become worse across 6metre band, more noticeable, whilst scanning the 6metre FM repeater segment, I did a sweep from 46-60 Mhz  and found there is wide band signal covering 52.500 to 57 MHz, the signal strength varies from s5 to s9 across that segment.
I suspect it radiating from Northern Beaches Hospital, possibly some piece of medical scanning equipment.
If scan across  the band with a narrow band receiver, it just seems like white noise, but the signal strength meter shows there is something there. 

This happened a few years ago and I tracked it to the hospital.and suddenly it went away.

UPDATE: 19 Feb 2026
I spent some time doing  better sweep, due to hearing some sort of buzz sound opening the mute on a repeater output frequency. Superimposed on that buzz sound is a click at approximately 1 per second rate, noted in the morning, afternoon and night at times when I checked. I swept from 46 to 60 MHz, these are the frequencies I noted the buzz sound on.
 these following frequencies were weak s0 but clearly audible :
50.030  50.060 51.280 51.870 52.140
these following frequencies were strong ie. s5 to s9 :
52.440  53.080  53.640  53.690  54.240  54.280  54.840  55.500  56.050  56.090
these following frequencies were weak s0 but clearly audible :
57.270  57.310  57.900  58.470  59.110  59.680  59.720

Overall, the raised S-meter was from 52.500 to 57 MHz,  where as the narrow bandwidth buzz sound is heard from  50MHz to 60MHz

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.

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

DMR hotspots and 70cm band Satellite segment interference

I have mentioned in the past, about people operating their DMR hotspots on strange frequencies,  ie. some in the 70cm weak signal segments, some on the band edge where they are in breach of their license conditions, but I also seen in the social media circles of people running their hotspots right in the Satellite segments of 2metre and 70cm bands.

I mean, just because your low powered hotspots ( typically mW) cant be heard when you drive down the road a couple kilometres, doesn't mean it cant be heard from a overhead satellite. Yes, low terrain kills your hotspot's  weak signal pretty quickly, but to an overhead satellite, your little digital hotspot at home can be easily heard and therefore causes interference to other modes used via the satellites.

I can't comprehend it, are amateur radio operators showing arrogance, or ignorance, or just plain stupidity ?    Well, just look at the Brandmeister dashboard you will see lots of them,  operating their hotspots smack in the middle of the satellite segments.  It would make you laugh, if it wasn't so serious.  We (licensed amateur radio operators) are supposed to be technical minded, who sat for a technical exam, yet some of us,  have no idea where we are running out DMR/MM hotspots, with respect to the bandplans designated against our licenses.   To use a phrase that celebrity chef,  Gordon Ramsay would probably say is :  "This is F###ing Incredible !!"

So, here they are :
the 2metre and 70cm Amateur Radio satellite segments
145.800 to 146.000 MHz
435.000 to 438.000 MHz
that means you don't run digital hotspots or any other RF devices in these segments, unless you intentionally plan to operate via one of the Amateur Radio Satellites and the designated modes.

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.