6 days of PLAs is enough - OK?

[GM4FVM]

Two weeks ago, on a Friday, I noticed interference on 4m. It took the form of groups of four carriers, about 50hz apart. The groups were spaced at about 40kHz intervals all across the band. The max strength was about S7, though not all four carriers were equal in strength. There was one right on the WSPR weak signal frequency. I use a Flex 1500 which is given to images, so although the groups of carriers were to either side of 70.200, an image was right on it. On FM there was a group of carriers on just about every channel. In addition to this there was hash everywhere. Although most HF bands were less affected by the carriers, the high noise level was everywhere. 2m was not affected.

This discovery came during antenna work here, so I spent some time fruitlessly examining what I had done. Eventually I noticed that I could get a beam heading on it, suggesting that it was nothing to do with my site, and I realised that the FM evidence meant that an entirely separate system with its own antenna was equally affected.

On Saturday I went out with my Wouxun and toured the area. A new solar panel installation was suspect, but it is noiseless as far as I can see. Eventually I found a great deal of noise coming from our pond pump. This was odd as the pump is at 90 degrees to the peak beam heading. After a great deal of disconnecting and tinkering at the pump it suddenly dawned on me that I could get the noise on the rig anywhere near our mains wires. the pump had simply been one source of the noise. It was everywhere in the house - my house.

Trying to notch the interference out using notch filters was pointless, as every so often the interference would change gear and move several kHz in either direction.

After more pondering, I recalled that a van had been parked next door on the Friday. I recognised the van as that used by the local antenna engineer, who doubles as general installer of technology round here. A quick enquiry revealed that a BT Vision system had been installed next door on the Friday morning. The house next door is fairly new, and open plan inside. I was surprised to find a Power Line Adapter (PLA) link had been used to connect the pre-existing BT router to the Vision box. Surprised, as BT say that if the router and the box are in the same room then they will be wired together. Although the two were about 4 metres apart, the only sensible wired route was via three walls and over two doors, an overall length of about 7 metres. Being a charitable soul, I supposed that was why the PLAs had been fitted, though I now think that this is done as a routine, however small the distances.

Needless to say, putting the Wouxun near the PLAs produced a howl of protest, and turning them off made the noise disappear. It was not so much that this interference was at its worst beside the PLAs, it was that the mess was appearing in my house wiring. My neighbour was very co-operative. She agreed to take it up with BT. In the meantime I just had to put up with it and try to think of what to do next. I thought that wiring the neighbour's house would be the best route, but she was not keen on that idea.

After an initial contact with BT, there was a long phone conversation with their help line. The BT guy had to endure alternating blasts from the neighbour and me. He was keen to deny any responsibility in all this. He also got confused as he tried to bring us back to the idea that this was a wi-fi problem. My neighbour eventually put a stop to that excuse by pointing out that her BT router had been there before the Vision installation. The guy tried to claim that he could not help with anything other than getting the BT gear to work and that anything else was "our problem". The neighbour put it very well "before the installation there was no problem, since the installation there is a problem, so you cannot keep saying that BT are not involved in fixing it". We were put on hold several times.

Eventually we were put through to a supervisor. He seemed to understand the problem but he was still pedalling the same line. He told me that "all electrical devices produce electro-magnetic interference", which was something to talk about, but maybe some other day. My neighbour kept battering him verbally. Eventually he said that the only way to solve the problem was to put a wired connection in - at my neighbour's expense. She was not keen on this but he said that BT would provide telephone support over to phone to explain how to install the cables ("clip it up, plug it in" I guess). He also persuaded us to try a replacement set of PLAs, which would be sent to my neighbour by post.

I left this as it was, but we all felt that wiring the house was the only real solution. Although the neighbour thought that I should not pay, I was prepared to buy the Ethernet cables and sockets she would need. I wanted to be sure that well screened leads were used.

The next day my neighbour phoned me to say "it is fixed". I was a bit doubtful about this, so I went round to see. She had moved the router to beside the TV and plugged it into the (main) BT socket which was located there. It turned out that, 3 years before when the house was being built, she had used the same guy who installed the Vision system to advise her then. He had advised her to get her main BT socket beside the TV "as internet TV is coming". To move the router she had to change the position of her internet phone, which had been connected to the router. She was happy enough to change all this around.

I had never realised that there was a BT socket beside her TV (actually, inside a cabinet). However, the installer who put the Vision box into the house must have been aware of it at some time, as it was his idea. It was him who told her to put it there, and it was also him who wired the extension socket which he later connected her router to. So despite the instructions from BT to connect it the router to the main socket, he had put it on an extension, and he had forgotten where he had specified the main socket to be.

So, the house is now wired - with BT phone cables.

That was a narrow escape. I only had to endure it from Friday until the following Wednesday. The only remaining effect seems to be hash from the TV or maybe poorly screened Ethernet cables on the new installation.

What I seem to have learned is:-
1) the installer will use PLAs whatever the layout of the house
2) BT help services find it hard to understand what you are talking about
3) wiring the house is indeed the only answer
4) check to see if a wired solution is available.
5) whatever the claims to have notched amateur bands out of the PLA range, 4m seemed to be worst affected
6) try to stay on good terms with your neighbours.

And finally:-

Do not have PLAs anywhere near you.

Jim
GM4FVM

[EI7GMB]

Hi Jim

Thats sad but true. PLA's BOPL' whatever you call it should be banned completely. In my case it knocks off the whole 160 to 20 meters (of what 160 and 80 meters are completely unusable) and then 4 and 2 meters (of what 2 meters is affected much more than 4m). No escape here, sadly. Cost of living in apartment complex. Got this interference on my hand held walking around the house. No other house in the area seem to have this thing, no other such a polluted area around, just mine.

Once upon the time I got a horrendous QRM on all 2m band. Tracked it down quite soon but was completely amazed what actually was the source of the interference - an USB sound card. When a music or a video was played then QRM suddenly was coming onto most of HF and the whole VHF spectrum, knocking off any signal around. When I unplugged headphones the QRM suddenly went away. A headphones lead worked as an antenna and actually any cable (ie USB extension lead or sound card to stereo lead) worked as a medium to spread the ssshhh.....noise. Just in case someone would like to know - A 5.1 USB dongle branded as Pentagram (yeah, hellish clamor indeed).

[GM4FVM]

Yes, you are right.

My tale was a long one, but at least I could do something about it.

I bought a laptop PSU from Paypal. and it was AWFUL.

I also have a KVM swtich to use one keyboard and mouse with two computers. I cannot route the video through it or I get a burbling sound everywhere. Still, I prefer two screens, so it does not cause much of a problem.

My XYL's printer also produces a beautiful carrier on 4m, but at least I can ask her to switch it off when not is use.

I guess all this is just a fact of modern life.

Jim
GM4FVM

[G8TOK]

Apologies; I have only just seen this post.

There is something else you can do. A neighbour had a similar BT installation fitted. After some DF I worked out where the noise was coming from.

I complained to OFCOM and an engineer appeared with astonishing speed. He kindly allowed me to walk along the street with him whilst he used his test gear to confirm the origin. He discovered that the two lamp standards adjacent to the property concerned were alive with RF and effectively acting like huge vertical aerials. The signals were coming down the mains, under the ground, and finding their way into the lamp standards. Further checks revealed that the house next door (a semi-detached) had it's wiring alive too.

He told BT to fix it, and they did so quickly. Unfortunately I was not allowed to know what was done, but given that the noise vanished totally I imagine it was hard wiring.

So... OFCOM can be on your side. Full credit to a pleasant and helpful gentleman.

73

Derek G8TOK

[G3PTU]

The Basic problem is that modern (and older for that matter) properties are simply not being built to suit the requirement for 21st Century Comunications. There is still the idea that the only phone socket should be in the Hallway! A new house near this residence has the telephone cable down the wall outside, stone house, botched up in the first week because of no internal wiring. Add to this that Joe public cannot even replace a tap washer nowadays.
It seems to me ludicious that while the public, government and Industry want us to become wired, that some form of easy comunication ducting is not provided in buildings. You cannot blame the basic premise that the ill-informed installer has to do the quickest easiest solution possible, he probably is only allowed a few minutes to do the whole job end to end. As for the Help deks - you might as well forget them, from one end of industry to the other, not fit for the purpose they are there for, simply a legal front to fend off the public, Try I**ea, B*Q, T*alkt*lk, V*gin. The real Piere de resitance is EDF France who have an english WWW Site , which will not accept Alpha-numeric postcodes. I rest my case melord.
David G3PTU

[G0EHV]

Hello,

I had the same thing here with my own BT Vision set up. I fixed it easily, see below -

Several months ago I got myself a BT Vision box and associated powerline
adaptors. Setting up with my BT Hub was easy and worked fine.
However the noise was horrendous on HF radio. Looking at the spectrum
revealed broadband HF noise from 2-30 MHz with quieter notches at the
amateur bands.
The SDR-IQ really showed what the spectrum was like!
Reception of all but the strongest stations was virtually impossible.

So, how to fix it.
First of all why not just throw away the adaptors and do without them? Well
the EPG is obtained from the hub, as is any downloaded media.
I needed the EPG hence I needed a link from the Vision box back to the hub.
The really easiest way is to run a CAT 5 cable and plug it up - hmmmmm, box
is in living room and hub upstairs.

The next easiest is to use the wireless network from the Home Hub.
I used another surplus hub as a "Wireless Access Point". The instructions
can be Googled and worked fine.
So I have the second hub sat behind the TV set and have no more QRM(N?). I
have the EPG and the I have tested downloaded media also.

Commercially, it would be as cheap to supply WAP's instead of powerline
adaptors, although it may not be as easily "Plug and Go" for the average
customer.



Hope this helps!