QRM

It’s amazing what a single wall-wart can do. I have some X10 controllers around the place controlling the outside lights and the dimmers in our family room. For ages now, one outside light refused to co-operate. I changed my scripts to fire several on or off commands to this light which worked for a time but then nothing. All the other lights seemed ok.

Then the family room lights would either come on or go off at random, but only occasionally. I went round the house with the ICR2 on MW and open squelch and there was a hash coming from one indoor camera but not the other. It also came out of many of the 13A sockets around the house. By now I was convinced I’d have multiple noise sources, potentially all of our wall-warts.

Anyway, it got to the stage that the X10 controller running from the house server could no longer reliably control any lights so I got another controller and ran that from the radio PC upstairs. That, at least got most lights back to normal operation, all except the one that had seemingly given up completely.

I finally made time to investigate more properly and began by unplugging the noisy cameral. Silence! All hash gone. Ok. Took the wall-wart out to the workshop and plugged it in. Instant hash, on or off load. I replaced it with another and although that camera still makes a hash on the ICR2 when close by there is nothing anywhere else in the house. And the X10 lights all work, controlled once more by the server, including that apparently uncooperative outside light.

I dismantled the offending wall-wart. It has the relevant filtering components so I assume one or more of them have gone duff over time.

Now, if I can just get rid of the ticking noises from the CAT5 cabling…

 

Rather obvious EMC problem…

I noticed just now that the Raspberry Pi that runs my ADBS receiver and also has ‘1-Wire’ temperature sensors for the central heating registered a pipe temperature of a theoretically impossible -1700C.

Oh, did I mention that my 20m / 6m dipole is in the loft… and the Pi is in the loft… about 2 feet from one leg of the dipole… Hmmm. I can see a connection here given the timestamp was the same as a JT65 transmission.

Noise…

Typical. I tidied the setup today and got everything into a better position for working – as you see in the photo now. And now there are stripes of noise across the waterfall in fldigi – as you can also see in the photo! I’ve moved everything about again to try to cure it to no avail. Something has clearly moved nearer to something else and they don’t get along. Grumble…