Broadband interference

💥 A general forum for topics not directly linked to SDR.
User avatar
m3ghe
Posts: 140
Joined: Sat Aug 08, 2020 2:58 pm
Location: Bedford
Contact:

Broadband interference

#1

Unread post by m3ghe »

Well that's my listening seriously curtailed.
This weekend broadband interference has appeared across the HF spectrum.
I have new neighbours one side but they are still waiting for their broadband to be connected and the other side say they haven't changed anything.
Really annoying as I went to all the trouble of eliminating it from my own broadband.
When it stops raining I will go out armed with smart phone and SDR to see if I can track the source.
Screenshot-2020-12-13-122041.jpeg
Screenshot-2020-12-13-122353.jpeg
Martin
m3ghe
IO92sc
G-QRP club 6129
Use my online radios http://remoteradio.myddns.me/ or http://remoteradio.changeip.org/

User avatar
KA1GJU
Posts: 264
Joined: Tue Aug 11, 2020 2:16 pm

Re: Broadband interference

#2

Unread post by KA1GJU »

Don't limit your search to 'Broadband Internet', could it be something your neighbors plugged in? Plasma TV, a computer UPS, cordless drill charger, etc?
Just make sure it's not something somebody plugged in at your QTH, before knocking on neighbors door. A little handheld HF rig, like the Yaesu FT-817 and a small whip for sniffing wires and equipment are handy for finding QRM. Any friends with something like that you can borrow for a few hours?

I started a thread long ago, "Place your QRM pictures here", on the Groups site, but all the images are now gone, but the text is still there.
https://sdr-radio.groups.io/g/main/message/38543
It appears to be 70kHz spacing on the traces, per the top image.

73 Kriss KA1GJU
73 Kriss KA1GJU Home of the KA1GJU Super Station SDRC Servers in NH, USA (FN42mw & FN43na)

User avatar
Simon G4ELI
Posts: 2134
Joined: Thu Aug 06, 2020 7:27 am
Location: Mawnan Smith
Contact:

Re: Broadband interference

#3

Unread post by Simon G4ELI »

Kriss,

If you want a QRM forum here it's fine - I archive every night to Dropbox.
Simon Brown :shock:
www.sdr-radio.com

Do not send me direct e-mail, thank-you!

User avatar
KA1GJU
Posts: 264
Joined: Tue Aug 11, 2020 2:16 pm

Re: Broadband interference

#4

Unread post by KA1GJU »

Did the images from days of yore all disappear for good? There was lots of good intel on those images. Reference the ones on Groups.io

Kriss
73 Kriss KA1GJU Home of the KA1GJU Super Station SDRC Servers in NH, USA (FN42mw & FN43na)

User avatar
Simon G4ELI
Posts: 2134
Joined: Thu Aug 06, 2020 7:27 am
Location: Mawnan Smith
Contact:

Re: Broadband interference

#5

Unread post by Simon G4ELI »

I stopped paying for the extra storage on groups.io, I'm paying attention to my costs which are quite considerable - soon I have to pay for the website & code-signing certificate, that's $700 and revenue is way, way down atm. Thanks goodness there's just myself and the dog to finance, I can just about stay on an even keel.
Simon Brown :shock:
www.sdr-radio.com

Do not send me direct e-mail, thank-you!

User avatar
G0OFE
Posts: 435
Joined: Thu Aug 06, 2020 7:33 am
Location: Sunny Sunny Bournemouth IO90BR
Contact:

Re: Broadband interference

#6

Unread post by G0OFE »

It's not plasma TV interference.. I know exactly what that looks like!

Hope you find the source and manage to get it sorted.
Jim, Bournemouth IO90BR
Image

User avatar
m3ghe
Posts: 140
Joined: Sat Aug 08, 2020 2:58 pm
Location: Bedford
Contact:

Re: Broadband interference

#7

Unread post by m3ghe »

KA1GJU wrote: Sun Dec 13, 2020 1:31 pm Don't limit your search to 'Broadband Internet', could it be something your neighbors plugged in? Plasma TV, a computer UPS, cordless drill charger, etc?
Just make sure it's not something somebody plugged in at your QTH, before knocking on neighbors door. A little handheld HF rig, like the Yaesu FT-817 and a small whip for sniffing wires and equipment are handy for finding QRM. Any friends with something like that you can borrow for a few hours?

I started a thread long ago, "Place your QRM pictures here", on the Groups site, but all the images are now gone, but the text is still there.
https://sdr-radio.groups.io/g/main/message/38543
It appears to be 70kHz spacing on the traces, per the top image.

73 Kriss KA1GJU
I ran a Lelantos test and it doesn't appear to be VDSL. So I will have to go hunting for the real culprit, what ever it is, is on 24/7, so unlikely to be a TV.
Yes the spacing is 74kHz across HF.

This has to be a SMPSU somewhere. I will do a house power down tomorrow and see what that produces.
Martin
m3ghe
IO92sc
G-QRP club 6129
Use my online radios http://remoteradio.myddns.me/ or http://remoteradio.changeip.org/

User avatar
m3ghe
Posts: 140
Joined: Sat Aug 08, 2020 2:58 pm
Location: Bedford
Contact:

Re: Broadband interference

#8

Unread post by m3ghe »

Powered down the house and the interference went.
Finally tracked it down to a length of CAT6e that runs from the switch upstairs to the downstairs switch feeding the TV and downstairs PC.
It runs along the outside wall between 2 houses and looks like it took a bashing when the new neighbours moved their belongings in.
New run installed now above head height.
Martin
m3ghe
IO92sc
G-QRP club 6129
Use my online radios http://remoteradio.myddns.me/ or http://remoteradio.changeip.org/

User avatar
KA1GJU
Posts: 264
Joined: Tue Aug 11, 2020 2:16 pm

Re: Broadband interference

#9

Unread post by KA1GJU »

I had to wrap my direct burial, shielded, cat6 around an FT-240-31 toroid coming into the repeater shed to quiet things down on my Super Station #2 server feeding a switch. Then all the cables exiting the switch had to be wound around the same style core to keep them quiet.
I bought a ten pack of these and only have a few left, they work GREAT! The more wraps, the better... but my CAT6 was stiff due to being direct burial, but inside a 4" conduit to run antenna control switching cables. You can literally watch the noise floor and the 74 kHz spikes get lower and lower until you max out the center of the core. You can get more turns on by placing the RG45 on AFTER threading the toroid.

The switch was radiating as well, so I wrapped it in thin peel-n-stick copper sheeting, and grounded it too.

Glad you found the problem, now hope the neighbors don't add to the noise floor!

73 Kriss KA1GJU
73 Kriss KA1GJU Home of the KA1GJU Super Station SDRC Servers in NH, USA (FN42mw & FN43na)

User avatar
m3ghe
Posts: 140
Joined: Sat Aug 08, 2020 2:58 pm
Location: Bedford
Contact:

Re: Broadband interference

#10

Unread post by m3ghe »

KA1GJU wrote: Mon Dec 14, 2020 3:09 pm I had to wrap my direct burial, shielded, cat6 around an FT-240-31 toroid coming into the repeater shed to quiet things down on my Super Station #2 server feeding a switch. Then all the cables exiting the switch had to be wound around the same style core to keep them quiet.
I bought a ten pack of these and only have a few left, they work GREAT! The more wraps, the better... but my CAT6 was stiff due to being direct burial, but inside a 4" conduit to run antenna control switching cables. You can literally watch the noise floor and the 74 kHz spikes get lower and lower until you max out the center of the core. You can get more turns on by placing the RG45 on AFTER threading the toroid.

The switch was radiating as well, so I wrapped it in thin peel-n-stick copper sheeting, and grounded it too.

Glad you found the problem, now hope the neighbours don't add to the noise floor!

73 Kriss KA1GJU
Oh all my cables have ferrite chokes and I built the router and switches into screened cabinets ages ago. the WiFi has antennas outside the screened boxes.
This is why I was convinced the interference was external to the house. I was right, just not quite what I was thinking though.
Martin
m3ghe
IO92sc
G-QRP club 6129
Use my online radios http://remoteradio.myddns.me/ or http://remoteradio.changeip.org/

Post Reply