Hi all
Anyone noticed an increase in local HF QRM in the last few days ? I have, with S9+ noise on 40m in particular.
It’s the nasty middle-kingdom SMPS on the Christmas lights ! Two sets of ours originally purchased from B&Q appear to be particular offenders. Fortunately, wrapping the DC output lead from the wall-wart about 10 turns through a FT140-43 toroid works wonders.
Cheers
Rick
No problems (thankfully) here - at least not as yet - we’ll see what happens nearer to Christmas.
73 Ed DD5LP.
Thats useful to consider - just put up an HF antenna on the roof , very noisy last night and was wondering if it was me or the bands or indeed the Christmas lights that were mandatory to put up and right outside the “shack”.
but worse on 2m i could hear some feint christmas tunes on RX when i receive from the local repeater, maybe simplex haven’t tried.
My plan was to kill the mains when the family is out and then bring up zone by zone and see whats what…
Hi Tim
Worth a try, unfortunately can’t do much about the neighbours’ ones !
Rick
yes, especially if i have to put up with their christmas tunes on 2m… that one is strange… i’m curious if its me, my neighbours (and if so why), or the cheap radio that maybe needs a bandpass filter.
You may also be getting it via the mains supply if the gear is running off a PSU.
There are mains filters that you can build to stop power carried QRM from neighbours on the same phase as you.
73 Ed.
Doesn’t seem to be a problem with mine. I guess about 10m of DC wiring makes a better antenna
Rick
The led christmas lights have definitely raised the local qrm at my station.
Here is some evidence in point from this afternoon on 40m. Rather unbelievable, but beautiful harmonics until I found the offending device, a christmas 12v transformer . rather close to the end of my end fed…
and later… problem solved…
Hi Tim,
An antenna over your roof can be an own goal. It’s close to all that meandering house wiring with connection to switchy digity thingos placed in every room, sometimes in clusters.
Powering off at the main switch while using a battery operated set could be revealing. Don’t forget to reset all those clocks and timers before the xyl comes home. Maybe just unplug one wall wart at a time or use a small portable radio as a sniffer.
Best of luck.
I was going to say go to a SOTA summit for a quiet radio life but a few days ago I was on Mt McKay which has a tower with lots of VHF and UHF and other stuff. The higher in frequency I went the worse it got. 40 m was OK mostly, 20 m had spots, 15 m had lots of spots and 10 m was nearly all spots - of wobbly signals spreading over several kHz.
73
Ron
VK3AFW
