[600MRG] photo of noise spikes here on 630M

[STEVE MCDONALD]

Hi Doug. Those are definitely crippling. The first thing I can ask is are you using an isolation transformer between the rx input and the antenna feedline? If not, crud like that from the shack (and its associated connection to the local power line ground) will be brought right out to the antenna location. Remember that every house in your immediate neighbourhood is connected to this same powerline and all can contribute noise. This transformer can be as simple as a few turns of light wire (1:1) on a ferrite toroid and can make a huge improvement.

As John indicated, sniff everything in the house for a sudden loud peak when you approach the possible culprit. A portable AM radio is ideal. I purposely bought an inexpensive Tecsun portable that tunes from LF to 30MHz just for this purpose. If it’s not in your own home then you have a bigger challenge. 

I start by trying to hear the crud on the portable and then DFing the direction with the radio’s built-in ferrite bar antenna. If the noise is coming from a neighbour then it’s being propagated along the powerlines and the DFing will often just point to the closest line. If that’s the case I will then walk through the neighbourhood until the signal falls off or gets stronger. Once you are close to the source it will be pretty loud and obvious. This has always been the case for me over the years and some of the sources can be a few blocks away as the powerlines make great antennas on these frequencies. Once you’ve determined the source then the rest is all diplomacy.

I’ve always explained that I’m trying to find the source of an electrical noise that is ‘destroying’ my shortwave radio reception and always let them hear the racket (usually VERY loud at their house). I have always met with an immediate positive response often accompanied with several apologies … followed by a quick fix. I find myself having to do this more and more often it seems, with the proliferation of inexpensive shoddily-designed crap from overseas. All we can do is to try and mitigate each one as it pops-up but I think hams are eventually going to lose this electronic whack-a-mole game eventually. 

Steve VE7SL 73
 
----- Original Message -----

Hey guys,
I'm hoping to be able to resume 2-way contacts soon. When I last operated
two years ago, I had almost no interference on 630M. Yesterday I mentioned
the noise spikes from an unknown source outside my home that now hinder my
630M reception.  Here's a photo of those noise spikes on both the Flex 6500
panadapter and on the WSJT-x graph.. You'll also see around 1490 Hz on the
WSJT-x graph the WSPR signal of N1DAY which is conveniently between noise
spikes.  Weak signals on the same frequencies as strong noise spikes don't
get decoded. The noise spikes are narrow band and equidistant apart, as you
can see, and some much stronger than others.  Any ideas on what this
interference could be or how I might try to trace it down?
Doug K4LY
Inman, SC

[image: 542e7757-d1e8-4a11-bdf4-948ea2bb3475.png]

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